Patent Application
20090057203
This invention relates to a process for separating a heavy hydrocarbon stream to produce an enriched saturates content stream(s) utilizing an ultrafiltration separations process. The enriched saturates content streams can then be further processed in refinery and petrochemical processes that will benefit from the higher content of saturated hydrocarbons produced from this separations process. The invention may be utilized to separate heavy hydrocarbon feedstreams, such as whole crudes, topped crudes, synthetic crude blends, shale oils, oils derived from bitumens, oils derived from tar sands, atmospheric resids, vacuum resids, or other heavy hydrocarbon streams into enriched saturates content product stream(s). The invention provides an economical method for separating heavy hydrocarbon stream components by molecular species instead of molecular boiling points.
As the demand for hydrocarbon-based fuels has increased, the need for improved processes for separating hydrocarbon feedstocks of heavier molecular weight has increased as well as the need for increasing the conversion of the heavy portions of these feedstocks into more valuable, lighter fuel products. These heavier, “challenged” feedstocks include, but are not limited to, low API gravity, high viscosity crudes from such areas of the world as the Middle East, Mexico, Venezuela, and Russia, as well as less conventional refinery feedstocks derived from such sources as bitumen, shale oil and tar sands. It is also important that heavy crude fractions, such as atmospheric resids, vacuum resids, and other similar intermediate feedstreams containing boiling point materials above about 850° F. are processed in such a manner so as to improve their ability to be utilized as feedstreams for subsequent refining and petrochemical processes such as, but not limited to, fuels blending, fuels upgrading, catalytic conversion, steam cracking, and lube oils production and upgrading.
Most crude oils and synthetic crude oils derived from such raw materials as bitumen, shale oil and tar sands are processed through initial separations units such as a crude unit that are designed to boil and distill lighter boiling point fractions from the heavier boiling point crude fractions. The majority of these boiling point fractions are sent to other refinery and petrochemical processes for further refinement depending upon their molecular content characteristics, while a smaller amount of these crude unit fractions are sent to finished product treatment and/or product blending.
One problem that exists is that these conventional separations units require a significant amount of energy to generate these distillation based separations. Most crude units have at least one atmospheric distillation train and at least one vacuum distillation train. Often crude units also have additional crude intermediate or auxiliary distillation trains. Each of these unit trains require the hydrocarbon feed to the train to be heated to temperatures of about 750° F. to about 850° F. prior to entering a distillation column associated with each train. In turn, each of these distillation columns normally requires multiple reflux circuits and possible intermediate column reheat circuits in order to properly control and achieve proper separation of the individual fractions obtained from the distillation. Not only does this arrangement require a significant amount of equipment and associated capital and maintenance costs, but these conventional processes require large amounts of input energy as well as a large array of sophisticated controls and skilled personnel for proper operation.
Another problem that exists in the art with heavy oils separations is that these crude distillation processes only separate the molecules of the feedstreams by boiling point. Therefore, molecules with close boiling points are removed together in a single fraction from the crude distillation processes. In particular saturated and aromatic hydrocarbons with the same or close carbon content (for example hexane and benzene which both have 6 carbon atoms) cannot be easily separated by commercial crude distillation processes and both molecules remain in a single stream of the crude unit fractions. Additionally, these types of molecules are very difficult to separate in subsequent refinery and petrochemical processes especially in distillation based processes. Most of the subsequent separations processes either rely on solution extraction processes or on other characteristics of the molecules such as their freeze points in order to separate these different close boiling point compounds. Therefore, as these ancillary processes tend to be expensive and very “targeted” as to the separations being achieved, typical refinery and petrochemical aromatics/saturates separations processes are generally limited to processes wherein a specific, small boiling point range of compounds are involved in the separation and/or wherein the separations must be made to within a high degree of purity.
Therefore, there exists in the industry a need for improved low energy refinery and petrochemical processes that can achieve a separation of hydrocarbon components by molecular species, in lieu of separations by molecular weight or boiling points. Even greater is the need for a relatively simple, low energy saturated hydrocarbons separations process that can make a bulk separation of high saturates content product streams from a heavy hydrocarbon feedstream, preferably a crude oil or crude resid hydrocarbon stream, without the use of conventional technologies for the separation of targeted molecular species such as extractive solvent processes.
This invention includes an ultrafiltration process for separating a heavy hydrocarbon containing stream to produce a permeate product stream with increased saturated hydrocarbons content stream utilizing an ultrafiltration separations process. In preferred embodiments, this invention may be utilized to separate heavy hydrocarbon feedstreams, such as whole crudes, topped crudes, synthetic crude blends, shale oils, oils derived from bitumens, oils derived from tar sands, atmospheric resids, vacuum resids, or other heavy hydrocarbon streams to produce a permeate product stream with increased saturated hydrocarbons content stream.
An embodiment of the present invention is a process for separating a heavy hydrocarbon stream, comprising:
a) contacting the heavy hydrocarbon stream with at least one porous membrane element in a membrane separation zone wherein the heavy hydrocarbon stream contacts a first side of the porous membrane element;
b) retrieving at least one permeate product stream from a second side of the porous membrane element, wherein the permeate product stream is comprised of selective materials which pass through the porous membrane element from the first side of the porous membrane element and are retrieved in the permeate product stream from the second side of the porous membrane element;
c) retrieving at least one retentate product stream from the first side of the porous membrane element;
d) conducting at least a portion of the permeate product stream to a first atmospheric distillation column;
e) retrieving a first atmospheric resid stream from the first atmospheric distillation column; and
f) conducting at least a portion of the first atmospheric resid stream to a first vacuum distillation column;
wherein the ratio of the saturates wt % content of the permeate product stream to the saturates wt % content of the heavy hydrocarbon stream is greater than 1.0.
Another embodiment of the present invention is a process for separating a heavy hydrocarbon stream, comprising:
a) conducting a heavy hydrocarbon stream to an atmospheric distillation column;
b) retrieving an atmospheric resid stream from the atmospheric distillation column;
c) contacting at least a portion of the atmospheric resid stream with at least one porous membrane element in a membrane separation zone wherein the atmospheric resid stream contacts a first side of the porous membrane element;
d) retrieving at least one permeate product stream from a second side of the porous membrane element, wherein the permeate product stream is comprised of selective materials which pass through the porous membrane element from the first side of the porous membrane element and are retrieved in the permeate product stream from the second side of the porous membrane element;
e) retrieving at least one retentate product stream from the first side of the porous membrane element;
f) conducting at least a portion of the permeate product stream to a first vacuum distillation column; and
g) retrieving a first vacuum resid stream from the first vacuum distillation column;
Another embodiment of the present invention is process for separating a heavy hydrocarbon stream, comprising:
a) contacting the heavy hydrocarbon stream with at least one porous membrane element in a membrane separation zone wherein the heavy hydrocarbon stream contacts a first side of the porous membrane element;
b) retrieving at least one permeate product stream from a second side of the porous membrane element, wherein the permeate product stream is comprised of selective materials which pass through the porous membrane element from the first side of the porous membrane element and are retrieved in the permeate product stream from the second side of the porous membrane element;
c) retrieving at least one retentate product stream from the first side of the porous membrane element;
d) conducting at least a portion of the permeate product stream to a storage tank;
e) conducting at least a portion of the permeate product stream from the storage tank to an atmospheric distillation column;
f) retrieving a first atmospheric resid stream from the first atmospheric distillation column; and
g) conducting at least a portion of the first atmospheric resid stream to a first vacuum distillation column;
wherein the ratio of the saturates wt % content of the permeate product stream to the saturates wt % content of the heavy hydrocarbon stream is greater than 1.0.
In other preferred embodiments, the porous membrane element is comprised of a material selected from ceramics, metals, glasses, polymers, and combinations thereof. In yet other preferred embodiments, the porous membrane element has an average pore size of about 0.001 to about 2 microns.
In other embodiments, the hydrocarbon stream in the membrane separation zone is maintained from about 100 to about 350° C. In still other embodiments, the transmembrane pressure across the porous membrane element is at least 400 psig.
This invention includes an ultrafiltration process for separating a heavy hydrocarbon stream to produce an enriched saturates content stream utilizing an ultrafiltration separations process. In preferred embodiments, this invention may be utilized to separate heavy hydrocarbon feedstreams, such as whole crudes, topped crudes, synthetic crude blends, shale derived oils, oils derived from bitumens, oils derived from tar sands, atmospheric resids, vacuum resids, or other heavy hydrocarbon streams to produce an enriched saturates content stream(s). Some of the terms utilized herein are defined as follows.
The term “saturates”, “saturated compounds”, or “saturated hydrocarbons” as used herein is defined as a hydrocarbon molecule containing only single molecular bonds (i.e., no double or triple molecular bonds). The term “aromatics” as used herein is defined as a compound molecule which includes a ringed molecular structure containing a delocalized π-electron system wherein the ring is comprised of at least one carbon atom and the ring contains at least one double molecular bond.
The term “average boiling point” as used herein is defined as the mass weighted average boiling point of the molecules in a mixture. This may be determined by simulated distillation gas chromatography (also referred to herein as “SIMDIS”). The term “initial boiling point” as used herein is defined as the temperature at which 5 wt % of the mixture is volatized at atmospheric (standard) pressure. The term “final boiling point” as used herein is defined as the temperature at which 95 wt % of the mixture is volatized at atmospheric (standard) pressure.
The term “hydrocarbon feedstream” or “hydrocarbon stream” as used herein is defined as a fluid stream that is comprised at least 80% hydrocarbon containing compounds by weight percentage.
The term “heavy hydrocarbon” or “heavy hydrocarbon feedstream” as used herein is defined as a hydrocarbon containing composition wherein the final boiling point as defined above is at least 1100° F.
The term “transmembrane pressure” as used herein is defined as the difference in pressure as measured across a membrane element being the difference in pressure between the higher pressure feed/retentate side of the membrane element and the lower pressure permeate side of the membrane elements.
The current invention can be utilized to separate a heavy hydrocarbon feedstream into at least one saturates enriched product stream. By use of the term “saturates enriched product stream”, it is meant that the wt % content of the saturated compounds in the saturates enriched product stream from the separation process is greater than the wt % content of the saturated compounds in the feedstream to the separation process. Conversely, by use of the term “saturates depleted product stream”, it is meant that the wt % content of the saturated compounds in the saturates depleted product stream from the separation process is less than the wt % content of the saturated compounds in the feedstream to the separation process.
An embodiment of the present invention is illustrated in
Continuing with
It is preferred that the membranes utilized in the present invention be constructed of such materials and designed so as to withstand prolonged operation at elevated temperatures and transmembrane pressures. In one embodiment of the present invention the membrane is comprised of a material selected from a ceramic, a metal, a glass, a polymer, or combinations thereof. In another embodiment, the membrane comprised of a material selected from a ceramic, a metal, or combination of ceramic and metal materials. Particular polymers that may be useful in embodiments of the present invention are polymers comprised of polyimides, polyamides, and/or polytetrafluoroethylenes provided that the membrane material chosen is sufficiently stable at the operating temperature of the separations process. In preferred embodiments, the membrane material has an average pore size of about 0.001 to about 2 microns (μm), more preferably about 0.002 to about 1 micron, and even more preferably about 0.004 to about 0.1 microns.
Although it is not believed to be necessary to obtain the separations results shown herein, it is preferable that the transmembrane pressure be above about 400 psi. It has been discovered that selective separation of certain components may be enriched at these higher transmembrane pressures. Preferably the transmembrane pressure is at least 700 psi, more preferably at least 1000 psi, even more preferably at least 1200 psi, and most preferably at least 1500 psi. The preferred transmembrane pressure ranges for operation of the present invention are about 400 to about 3000 psi, more preferably about 500 to about 2500 psi, even more preferably about 700 to about 1500 psi.
Also, in other preferred embodiments of the present invention, the temperatures of the heavy hydrocarbon feedstream when contacting the membrane element is from about 100 to about 350° C., and more preferably about 100 to about 300° C. For heavy hydrocarbon feedstreams containing a substantial portion of vacuum resids, the most preferable temperature is about 200 to about 300° C. The current invention can operate at feedstream temperatures above 350° C., but it is preferred that the feedstream be below a temperature wherein thermal cracking of the feedstream is minimized.
Continuing with
In a preferred embodiment, the heavy hydrocarbon feedstream is flowed across the face of the membrane element(s) in a “cross-flow” configuration. In this embodiment, in the retentate zone, the heavy hydrocarbon feed contacts one end of the membrane element and flows across the membrane, while a retentate product stream is withdrawn from the other end of the retentate zone. As the feedstream/retentate flows across the face of the membrane, a composition selective in saturated compounds content flows through the membrane to the permeate zone wherein it is drawn off as a permeate product stream. In a cross-flow configuration, it is preferable that the Reynolds number in at least one retentate zone of the membrane separations unit be in the turbulent range, preferably above about 2000, and more preferably, above about 4000. In some embodiments, a portion of a retentate stream obtained from the membrane separation units may be recycled and mixed with the feedstream to the membrane separations unit prior to contacting the active membrane.
Example 1 illustrates an embodiment of the present invention wherein the heavy hydrocarbon feedstream utilized in the ultrafiltration process was a commercial grade crude atmospheric distillation column resid product stream. In this example, the transmembrane pressure was held at 1000 psi and the temperature was varied from about 150° C. to about 300° C.
The results from an ultrafiltration process of the present invention from Example 1 are shown in Table 1 herein. As can be seen from the data in Table 1, the saturates content of the permeate products were consistently higher than all of the retentate samples. The permeate samples that were analyzed for saturates content all showed higher wt % saturates than the initial feed. Permeate Sample 1 showed a saturates concentration of 20.5 wt % which is 1.18 times the saturates content of the Atmospheric Resid Feed to the ultrafiltration separations unit. Similarly, the saturates concentration of Permeate Samples 3, 5, and 10 were 27.4 wt %, 33.4 wt %, and 21.0 wt %, respectively, which equates to a saturates content in the permeate ranging from about 1.58 to about 1.93 times the saturates content in the heavy hydrocarbon feed to the ultrafiltration separations unit. As further explained in Example 1, due to the recycle of the retentate stream to the feed supply chamber during the test in Example 1, a better comparison of the actual saturates content of the feedstream at a particular point in the experiment is represented by retentate samples that were taken at nearly the same point in the experiment as its corresponding permeate sample. When the saturates content of the permeate samples were compared to the saturates content of the retentate samples taken at corresponding points in the experiment, the permeate stream obtained achieved saturates contents of about 2.5 times the saturate content of the corresponding retentate (i.e., representative of the saturates content of the corresponding feed at the point in the experiment).
In an embodiment of the present invention, a heavy hydrocarbon feedstream is contacted with a porous membrane element and a permeate product stream is obtained wherein the ratio of the wt % saturates content of the permeate stream to the wt % saturates content of the heavy hydrocarbon feedstream is at least about 1.2. In another embodiment, the ratio of the wt % saturates content of the permeate stream to the wt % saturates content of the heavy hydrocarbon feedstream is at least about 1.5. In a still another embodiment, the ratio of the wt % saturates content of the permeate stream to the wt % saturates content of the heavy hydrocarbon feedstream is at least about 2.0.
Example 2 and corresponding
In other preferred embodiments of the process of the current invention, the average of the saturates wt % content of the permeate to the saturates wt % content of the retentate for the components fractions with boiling points below about 900° F. is greater than about 1.5, more preferably greater than about 2.0. Similarly, in preferred embodiments of the process of the current invention, the average of the saturates wt % content of the permeate to the saturates wt % content of the retentate for the components fractions with boiling points below about 1100° F. is greater than about 1.2, more preferably greater than about 1.5.
As discussed above, these saturates enriched product streams are valuable feedstocks for additional upgrading processes in refinery and petrochemical plants. Conversely, the saturates depleted product streams can also be utilized to target specific processes wherein the decreased content of saturated hydrocarbons may be beneficial and may also assist in debottlenecking or increasing the rate on such processes wherein the saturates enriched stream does not require the upgrading or the extent of upgrading and through this process can be excluded from further processing.
In this embodiment, the saturates enriched permeate product stream (330) or a portion thereof is further processed as a feedstream to a first atmospheric distillation column (335) and a first atmospheric resid stream (340) is drawn from the first atmospheric distillation column and at least a portion of the first atmospheric resid stream is utilized as a feed to a first crude vacuum distillation column (345). The atmospheric resid stream typically is comprised of hydrocarbon compounds with an initial boiling point of at least about 650° F. (343° C.) at atmospheric pressure. For clarity, associated auxiliary equipment as well as optional column distillations are not shown in
A first vacuum gas oil (“VGO”) stream (350) is preferably drawn from the first vacuum distillation column (345). The VGO stream typically has a boiling range of about 650 to about 1050° F. at atmospheric pressure. Since this first VGO stream will be higher in saturates content than if the heavy oil was not first processed in the membrane separations unit (305) of the present invention, the VGO will be of a composition for an improved feed to a steam cracker unit, lubes extraction/dewaxing unit, lubes hydrocracker unit or a lubes hydrodewaxing unit. In a preferred embodiment, at least a portion of the first VGO stream (350) is sent to a steam cracker unit, lubes extraction/dewaxing unit, lubes hydrocracker unit or a lubes hydrodewaxing unit. It should be noted that with the present invention, due to the unique compositional separations it can obtain, it may be possible to make an enriched saturates content VGO from a crude or heavy hydrocarbon feed which may be utilized as a lube basestock feed from crudes or heavy hydrocarbon feeds that otherwise would not be able to produce a VGO stream with properties sufficient to produce commercial grade lubricant oils. This enriched saturates content VGO stream can be an excellent feedstock for producing commercial grade lubricants.
Similarly, the first vacuum resid stream (355) from the first vacuum distillation column (345) will be higher in saturates content than if the heavy hydrocarbon feedstream was not first processed in the membrane separations unit (305) of the present invention. The vacuum resid stream typically has a final boiling point of greater than about 1100° F. at atmospheric pressure. This enriched saturates content vacuum resid stream can be an excellent feedstock for producing commercial grade heavy lubricants. With the present invention, due to the unique compositional separations it can obtain, it may be possible to make an enriched saturates content vacuum resid from a crude or heavy hydrocarbon feed which may be utilized as a lube basestock feed from crudes or heavy hydrocarbon feeds that otherwise would not be able to produce a vacuum resid stream with properties sufficient to produce commercial grade lubricant oils. In a preferred embodiment at least a portion of the first vacuum resid stream (355) is further processed in a solvent deasphalter unit wherein the solvent deasphalter product is utilized in the production of a lube oil. In a preferred embodiment, the levels of asphaltenes in the first vacuum resid stream (355) may be at a low enough level to allow at least a portion of the second vacuum resid stream to be processed in a lube extraction unit or dewaxing unit without the need for solvent deasphalting.
Continuing with
A second virgin gas oil (or “VGO”) stream (375) is preferably drawn from the second vacuum distillation column (370). The VGO stream typically has a boiling range of about 650 to about 1050° F. at atmospheric pressure. In a preferred embodiment, at least a portion of the second VGO stream (375) is sent for further processing in a catalytic cracking (“FCC”) unit, a hydrodesulfurization unit, and/or a fuels hydrocracking unit.
The second vacuum resid stream (380) from the second vacuum distillation column (370) stream will be lower in saturates content than if the heavy hydrocarbon feedstream was not first processed in the membrane separations unit (305) of the present invention. The vacuum resid stream typically has a final boiling point of greater than about 1100° F. at atmospheric pressure. In a preferred embodiment at least a portion of the second vacuum resid stream (380) is further processed in a Fluid Coking unit, a Flexicoking unit or a delayed coking unit. In another preferred embodiment at least a portion of the second vacuum resid stream (380) is further processed in a visbreaking unit, a partial oxidation (“POX”) unit or in a carbon black production unit. Most preferably, the second vacuum resid stream (380) is utilized in an asphalt unit or a fuel oil production unit.
In another embodiment, a portion of the retentate product stream (325) is segregated into a second retentate stream (395) and sent to a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, an asphalt production unit, or a fuel oil production unit. In still another embodiment, all of the retentate product stream (325) bypasses the second atmospheric distillation column and second vacuum distillation column thereby eliminating the need for the second atmospheric and second vacuum distillation columns and associated equipment, and at least a portion of the second retentate stream (395) is sent to a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, an asphalt production unit, or a fuel oil production unit.
Here, in
In this embodiment, the enriched-saturates content permeate product stream (435) or a portion thereof is processed further processed as a feedstream to a first vacuum distillation column (440). A first vacuum gas oil (“VGO”) stream (445) is preferably drawn from the first vacuum distillation column (440). The VGO stream typically has a boiling range of about 650 to about 1050° F. at atmospheric pressure. Since this first VGO stream will be higher in saturates content than if the atmospheric resid stream was not first processed in the membrane separations unit (415) of the present invention, the VGO will be of a composition for an improved feed to a steam cracker unit, lubes extraction/dewaxing unit, lubes hydrocracker unit or a lubes hydrodewaxing unit. In a preferred embodiment, at least a portion of the first VGO stream (445) is sent to a steam cracker unit, lubes extraction/dewaxing unit, lubes hydrocracker unit or a lubes hydrodewaxing unit. It should be noted that with the present invention, due to the unique compositional separations it can obtain, it may be possible to make an enriched saturates content VGO from a crude or heavy hydrocarbon feed which may be utilized as a lube basestock feed from crudes or heavy hydrocarbon feeds that otherwise would not be able to produce a VGO stream with properties sufficient to produce commercial grade lubricant oils. This enriched saturates content VGO stream can be an excellent feedstock for producing commercial grade lubricants.
Similarly, the first vacuum resid stream (450) from the first vacuum distillation column (440) will be higher in saturates content than if the heavy hydrocarbon feedstream was not first processed in the membrane separations unit (415) of the present invention. The vacuum resid stream typically has a final boiling point of greater than about 1100° F. at atmospheric pressure.
This enriched saturates content vacuum resid stream can be an excellent feedstock for producing commercial grade heavy lubricants. With the present invention, due to the unique compositional separations it can obtain, it may be possible to make an enriched saturates content vacuum resid from a crude or heavy hydrocarbon feed which may be utilized as a lube basestock feed from crudes or heavy hydrocarbon feeds that otherwise would not be able to produce a vacuum resid stream with properties sufficient to produce commercial grade lubricant oils. In a preferred embodiment at least a portion of the first vacuum resid stream (450) is further processed in a solvent deasphalter unit wherein the solvent deasphalter product is utilized in the production of a lube oil. In a preferred embodiment, the levels of asphaltenes in the first vacuum resid stream (450) may be at a low enough level to allow at least a portion of the second vacuum resid stream to be processed in a lube extraction unit or dewaxing unit without the need for solvent deasphalting.
The saturates depleted retentate product stream (455) may be utilized as a feed to a second vacuum distillation column (460). The dispositions of the vacuum distillation column product streams of the present embodiment are similar to the those shown in the embodiment of
In the embodiment of
In another embodiment, a portion of the depleted retentate product stream (455) is segregated into a second retentate stream (475) and sent to a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, a fuel oil production unit, a visbreaker unit, or an asphalt unit. In still another embodiment, all of the depleted retentate product stream (455) bypasses the second vacuum distillation column thereby eliminating the need for the second vacuum distillation column and associated equipment, and at least a portion of the second retentate stream (475) is sent to a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, a fuel oil production unit, a visbreaker unit, or an asphalt unit.
Although the embodiments of the present invention illustrated in
In this embodiment, from 0 to 100% of the permeate product stream (530) can be segregated into a permeate tankage inlet stream (535) and an atmospheric distillation column permeate feedstream (540). Similarly, from 0 to 100% of the retentate product stream (525) can be segregated into a retentate tankage inlet stream (545) and an atmospheric distillation column retentate feedstream (550). In this manner, at any given time, from 0 to 100% of the permeate product stream (530) can be fed to the atmospheric distillation column (580) and from 0 to 100% of the retentate product stream (525) can be fed to the atmospheric distillation column (580). At any given time, from 0 to 100% of the permeate product stream (530) can be segregated into a permeate tankage inlet stream (535) and stored in the permeate product tank (555). As required, the stored permeate product can be removed from storage as a permeate tankage outlet stream (565) and reintroduced into the combined atmospheric distillation column feedstream (575) to the atmospheric distillation column (580). In a similar manner, at any given time, from 0 to 100% of the retentate product stream (525) can be segregated into a retentate tankage inlet stream (545) and stored in the retentate product tank (560). As required, the stored retentate product can be removed from storage as a retentate tankage outlet stream (570) and reintroduced into the combined atmospheric distillation column feedstream (575) to the atmospheric distillation column (580).
This embodiment allows the segregated permeate and retentate product streams to be recombined in ratios to allow continuous or block operations of the atmospheric distillation column feedstream. In block operations, the permeate product and retentate concentrations of the atmospheric distillation column feedstream would be altered during different blocks of time to allow for differing product compositions to be obtained from the single atmospheric distillation column (580) and single vacuum distillation column (584).
Continuing with
A vacuum resid stream (588) is drawn from the vacuum distillation column (584). While the atmospheric distillation column feedstream (575) is significantly concentrated in permeate product as compared to retentate product, at least a portion of the vacuum resid stream (588) with an improved saturates content is further processed in a solvent deasphalter unit wherein the solvent deasphalter product is utilized in the production of a lube oil. While the atmospheric distillation column feedstream (575) is highly concentrated in retentate product as compared to permeate product, at least a portion of the vacuum resid stream (588) with a depleted saturates content is further processed in a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, a visbreaking unit, a partial oxidation (“POX”) unit, a carbon black production unit, an asphalt unit or a fuel oil production unit.
Another embodiment is illustrated in
In this embodiment, from 0 to 100% of the permeate product stream (635) can be segregated into a permeate tankage inlet stream (645) and a vacuum distillation column permeate feedstream (650). Similarly, from 0 to 100% of the retentate product stream (640) can be segregated into a retentate tankage inlet stream (655) and a vacuum distillation column retentate feedstream (660). In this manner, at any given time, from 0 to 100% of the permeate product stream (635) can be fed to the vacuum distillation column (684) and from 0 to 100% of the retentate product stream (640) can be fed to the vacuum distillation column (684). At any given time, from 0 to 100% of the permeate product stream (635) can be segregated into a permeate tankage inlet stream (645) and stored in the permeate product tank (665). As required, the stored permeate product can be removed from storage as a permeate tankage outlet stream (670) and reintroduced into the combined vacuum distillation column feedstream (682) to the vacuum distillation column (684). In a similar manner, at any given time, from 0 to 100% of the retentate product stream (640) can be segregated into a retentate tankage inlet stream (655) and stored in the retentate product tank (675). As required, the stored retentate product can be removed from storage as a retentate tankage outlet stream (680) and reintroduced into the combined vacuum distillation column feedstream (682) to the vacuum distillation column (684).
This embodiment allows the segregated permeate and retentate product streams to be recombined in ratios to allow continuous or block operations of the vacuum distillation column feedstream. In block operations, the permeate product and retentate concentrations of the vacuum distillation column feedstream would be altered during different blocks of time to allow for differing product compositions to be obtained from single vacuum distillation column (684).
Continuing with
A vacuum resid stream (688) is drawn from the vacuum distillation column (684). The vacuum resid stream typically has final boiling point of greater than about 1100° F. at atmospheric pressure. When the vacuum distillation column feedstream (682) is significantly concentrated in permeate product as compared to retentate product, at least a portion of the vacuum resid stream (688) with an improved saturates content is further processed in a solvent deasphalter wherein the solvent deasphalter product is utilized in the production of a lube oil. When the vacuum distillation column feedstream (682) is significantly concentrated in retentate product as compared to permeate product, at least a portion of the vacuum resid stream (688) with a depleted saturates content is further processed in a Fluid Coking unit, a Flexicoking unit, a delayed coking unit, a visbreaking unit, a partial oxidation (“POX”) unit, a carbon black production unit, an asphalt unit or a fuel oil production unit.
Although the present invention has been described in terms of specific embodiments, it is not so limited. Suitable alterations and modifications for operation under specific conditions will be apparent to those skilled in the art. It is therefore intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.
The Examples below are provided to illustrate the improved product qualities and the benefits from specific embodiments of the current invention for producing an improved product stream from a heavy hydrocarbon containing feedstream via ultrafiltration with the membranes and operating conditions of the present invention. These Examples only illustrate specific embodiments of the present invention and are not meant to limit the scope of the current invention.
In this Example, a commercial crude distillation unit atmospheric resid was utilized as the heavy hydrocarbon feedstream to the ultrafiltration process. The atmospheric resid was permeated in a batch membrane process using an 8 kD (kiloDalton) ceramic disk ultrafiltration membrane. The pore size of this membrane was estimated to be in the 0.005 to 0.010 micron (μm) range. The transmembrane pressure was held at 1000 psig and the feed temperature was adjusted between 150 to 300° C. during the test. The separations process was in a crossflow configuration wherein the hydrocarbon feedstream was flowed across the face of the membrane and the retentate was collected and returned to a feed supply chamber containing the hydrocarbon feedstream. Select permeate samples and retentate samples were extracted during the test and the flux rates and permeate yields were measured during testing. Select samples were analyzed for saturates, aromatics, resin, and polars content in an latroscan analyzer.
The latroscan analysis procedure utilized is described further as follows. The latroscan performs quantitative analysis by detection of zones separated on a Chromorod thin layer using a GC type hydrogen Flame Ionization Detector (FID). The Chromorod is a quartz rod coated with a thin layer of sintered silica or alumina on which the sample is developed and separated at an advanced constant speed through a hydrogen flame by which the organic substance is separated on the thin layer and ionized through the energy obtained from the flame. Affected by an electric field applied to the poles of the FID, the ions generate an electric current with the intensity proportional to the amount of each organic substance entering the flame thereby enabling a quantitative determination. Typically, 1 microliter of a sample is spotted at a marked position on the Chromorod. The rods are placed in solvent tanks for varying times for “development.” The rods are dipped in the tanks to the level where the rod was spotted with the sample. Development, i.e. moving the species down the length of the rod is done at room temperature. In the First Phase of Development, n-Heptane is utilized for 35 min. (moves the Saturates). In the Second Phase of Development, Toluene is utilized for 15 min. (moves the Aromatics). In the Third Phase of Development, Methylene Chloride/Methanol at 0.95/0.5 ratio is utilized for 2 min. (moves the Resins). The fourth group, i.e., the Polars, remains near the spotting location. The sample rods are then fed at a controlled rate through a hydrogen flame to create the gases analyzed by FID. Generally four well separated peaks are quantified.
The test conditions, flux rates, yields, and select permeate and retentate latroscan compositional results are tabulated in Table 1. As noted above, the retentate obtained from the process was recycled to a feed chamber containing the hydrocarbon feedstream (i.e., the atmospheric resid) and both overall feed supply and the retentate were over the course of the experiment gradually depleted of the components contained in the permeate. As can be seen from the data in Table 1, the saturates content of the permeate products obtained were consistently higher than all of the retentate samples during the testing. It should be noted that although the latroscan analysis utilized in analyzing the samples this Example separates the components into “Saturates”, “Aromatics”, “Resins” and “Polars”, the Resins and Polars are primarily aromatic molecules and a total “aromatics” content of a sample as defined in the definitions above is best estimated by summing the values of the “Aromatics”, “Resins” and “Polars” for each sample shown in Table 1. The total “saturates” content of a sample as defined in the definitions above is approximately the value of the “Saturates” as shown in Table 1.
Referring to Table 1, the original Atmospheric Resid Feed had a saturates content of 17.3 wt %. The first permeate sample (Permeate Sample 1) retrieved from the process was analyzed and as can be seen, had a saturates content of 20.5 wt % which is an 18% increase (1.18 times) in saturates content as compared to the feedstream. Permeate Sample 3 which was obtained a little further into the run under the same process conditions as Permeate Sample 1 better exemplifies the steady states condition of the process as compared to Permeate Sample 1. Here, Permeate Sample 3 had a saturates content of 27.4 wt % which is a 58% increase (1.58 times) in saturates content a compared to the Atmospheric Resid Feed. It is noted that the actual increase in saturates between the permeate-side and the feed-side streams was probably even greater than this as it is noted above in that the retentate recycle was continually decreasing in its overall saturates content in the feedstream to the membrane module. Comparison of the results of Permeate Sample 5 and Retentate Sample 5 in Table 1 exemplifies this point.
As can be seen from Table 1, Permeate Sample 5 had a saturates content of 33.4 wt %. A sample of the retentate (Retentate Sample 5) was taken at about the same point in the experiment and analyzed for content. This Retentate Sample 5 had a saturates content of only about 12.9 wt % and is a close representative of the composition of the feedstream at the time that Permeate Sample 5 was taken. Reviewing the compositions, Permeate Sample 5 had a saturates content that was 93% greater (1.93 times) than the saturates content of the initial Atmospheric Resid Feed and 159% greater (2.59 times) than the saturates content of Retentate Sample 5 which closely resembles the composition of the feed when Permeate Sample 5 was taken.
The final permeate sample (Permeate Sample 10) from the experimental example run was analyzed as well as a corresponding final retentate sample (Retentate Sample 10). Analyzing this data similar to Samples 5 above, Permeate Sample 10 had a saturates content of 21.0 wt %. A corresponding sample of the retentate (Retentate Sample 10) was taken at about the same point in the experiment and analyzed for content. This Retentate Sample 10 had a saturates content of only about 11.8 wt % and is a close representative of the composition of the feedstream at the time that Permeate Sample 10 was taken. Reviewing the compositions, Permeate Sample 10 had a saturates content that was 21% greater (1.21 times) than the saturates content of the initial Atmospheric Resid Feed and 78% greater (1.78 times) than the saturates content of Retentate Sample 10 which closely resembles the composition of the feed when Permeate Sample 10 was taken.
This example shows that a heavy hydrocarbon stream can be separated according to ultrafiltration process of the presently claimed invention to produce a permeate product stream with a significantly improved saturates content.
In this Example, additional separations and analyses were performed on Permeate Sample 5 and Retentate Sample 5 obtained from Example 1 above. Each of these two samples were separated into saturates, aromatics, resins, and asphaltenes components by a silica-gel SARA analysis (which is known in the art). The component samples were then analyzed with a Simulated Distillation gas chromatography analysis (“SIMDIS”) to determine the boiling point distribution of each of the component samples. The data obtained from the SIMDIS analysis of the saturates components obtained from Permeate Sample 5 were compared to the data obtained from the SIMDIS analysis of the saturates components obtained from Retentate Sample 5. The results are presented in
As can be seen in
These examples illustrate the significantly increased saturates content streams that can be produced in accordance with the present invention.
This application claims the benefit of U.S. Provisional Application No. 60/966,469 filed Aug. 28, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60966469 | Aug 2007 | US |
