Abstract
A process for creating higher quality and lower quality base oils from used lubricating oils and crude oils, wherein the higher quality base oils may be either Group III or Group II and the lower quality base oils may be either Group II or Group I. Vacuum gas oils produced from used lubricating oils and from crude oils are processed via two or more process steps, including solvent extraction, solvent or catalytic or iso dewaxing, and hydrotreating. Such process enables efficient conversion and operation of refineries formerly capable only of making Group I base oils, even as their ability to make heavier base oils, waxes, and bright stocks is preserved, substantially to the same extent as such products had been made prior to undertaking the conversion.
Claims
1. A method for making base oil, the method comprising steps of: blending together (a) vacuum gas oil made from crude oil (CO-VGO) and (b) vacuum gas oil made from used lubricating oil (UO-VGO) to form a blended VGO (Blended VGO); and processing the Blended VGO by means of at least two of solvent extraction, dewaxing, and hydrotreating to make a base oil.
2. A method for making base oil by solvent extraction, de-waxing, and hydrotreating, the method comprising steps of: processing vacuum gas oil made from crude oil (CO-VGO) during a first period of time by at least two of solvent extraction, dewaxing, and hydrotreating to make at least one first base oil; and processing vacuum gas oil made from used lubricating oil (UO-VGO) during a second period of time by at least two of solvent extraction, dewaxing, and hydrotreating to make at least one second base oil.
3. The method of claim 2 wherein the UO-VGO is processed by hydrotreating prior to processing by solvent extraction.
4. The method of claim 2 wherein the UO-VGO is processed by solvent extraction prior to processing by hydrotreating.
5. The method of claim 3 wherein at least a portion of the effluent produced after processing the UO-VGO by hydrotreating is then processed by solvent extraction.
6. The method of claim 4 wherein at least a portion of the effluent produced after processing the UO-VGO by solvent extraction is then directly processed by hydrotreating.
7. The method of claim 2 wherein at least a portion of the at least one second base oil produced from processing UO-VGO is a Group III base oil.
8. The method of claim 2 wherein at least a portion of the at least one second base oil produced from processing the UO-VGO is a Group II base oil.
9. The method of claim 2 wherein at least a portion of the at least one first base oil produced from processing the CO-VGO is a Group II base oil.
10. The method of claim 2 wherein UO-VGO has a viscosity index in excess of 100.
11. The method of claim 2 wherein UO-VGO has a viscosity index in excess of 105.
12. The method of claim 2 wherein UO-VGO has a viscosity index in excess of 110.
13. The method of claim 2 wherein UO-VGO has a viscosity index in excess of 115.
14. A method for making at least one of a first base oil and a second base oil, the method comprising the steps of processing a vacuum gas oil that is made from used lubricating oil (UO-VGO) that has a viscosity index (VI) of 90 or more by means of at least two of solvent extraction, dewaxing, and hydrotreating.
15. The method of claim 14 wherein the UO-VGO has a VI in excess of 105.
16. The method of claim 14 wherein the UO-VGO has a VI in excess of 110.
17. The method of claim 14 wherein the UO-VGO has a VI in excess of 115.
18. The method of claim 14 wherein solvent extraction precedes hydrotreating.
19. The method of claim 14 wherein hydrotreating precedes solvent extraction.
20. The method of claim 14 where at least a portion of the UO-VGO is processed into a Group III base oil.
21. The method of claim 14 wherein at least a portion of the UO-VGO is processed into a Group II base oil.
22. A method of processing at least one of CO-VCB and UO-VCB by means of solvent deasphalting wherein the deasphalted oil produced by solvent deasphalting the at least one of CO-VCB and UO-VCB is then further processed into bright stock.
23. The method of claim 22 wherein the deasphalted oil is then blended into at least one of CO-VGO and UO-VGO.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
[0046] FIG. 1 is a schematic diagram of multiple pathways to produce base oils from crude oils in accordance with the prior art.
[0047] FIG. 2 is a schematic diagram of multiple pathways to produce base oils from using lubricating oils in accordance with the prior art.
[0048] FIG. 3 is a schematic diagram exemplifying a preferred embodiment of the invention where CO-VGO is processed in a substantially similar way as per the traditional sequence in making Group I base oils, and UO-VGO is processed in a preferred sequence of hydrotreating before solvent extraction in making Group III base oils.
[0049] FIG. 4 is a schematic diagram exemplifying a first alternative embodiment of the invention where CO-VGO and UO-VGO may be blended together and processing occurs in which hydrotreating precedes solvent extraction.
[0050] FIG. 5 is a schematic diagram exemplifying a second alternative embodiment of the invention where CO-VGO and UO-VGO may be blended together and the processing occurs where solvent extraction precedes hydrotreating, thus necessitating a blocked out configuration which requires storage of intermediate raffinate and extract liquids.
[0051] FIGS. 6A, 6B, and 6C exemplify three distinct modes in which CO-VGO and UO-VGO may be processed either singly, or in blended form as achieved by gate valves, a blending (proportional) valve, or check valves.
DETAILED DESCRIPTION OF THE INVENTION
[0052] Refer now to the drawings wherein depicted elements are, for the sake of clarity, not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views. In the interest of conciseness, well-known elements may be illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail, and details concerning various other components known to the art, such as solvent extraction extraction units, hydrotreaters, and the like necessary for the operation of many oil and gas processes, have not been shown or discussed in detail inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons of ordinary skill in the relevant art. Additionally, as used herein, the term substantially is to be construed as a term of approximation.
[0053] FIG. 3 presents a preferred configuration in which CO-VGO is processed using the traditional solvent extraction, solvent dewaxing (which could be catalytic dewaxing), and hydrofinishing sequence. When UO-VGO is being run, the assumption in FIG. 3 is that the hydrofinishing has preferably been upgraded to hydrotreating, if and as needed the solvent extraction unit has also been upgraded, and that an additional fractionation capability may optionally be added so as to provide continuous fractionation of both the higher valued (primarily Group III) stream and the lower valued Group II stream. FIG. 3 thus assumes that CO-VGO and UO-VGO will each be run separately through the plant at different times (i.e., blocked out). In FIG. 3, the solid lines represent processing of CO-VGO and the dotted lines represent processing of UO-VGO. An explanation of processing for each of the CO-VGO and UO-VGO streams follows next below.
[0054] In FIG. 3, CO-VGO 300 is charged first to solvent extraction unit 311, and the extract (which is a low value stream) is then generated as stream 313. Also charged to solvent extraction unit 311 is CO-DAO 307 generated by solvent de-asphalting unit 305, which has been generated from the vacuum column bottoms CO-VCB 303. The separate or blended processing of UO-VCB 304 is presented as a further option from which is then generated UO-DAO 308 which is passed to solvent extraction unit 311. Also generated in solvent de-asphalting unit 305 are one or more asphalt-like products shown as CO-Asphalt 309 and UO-Asphalt 310.
[0055] The raffinate from solvent unit 311 is then passed to solvent dewaxing step 316 (which could instead be catalytic dewaxing or iso-dewaxing) whereupon wax products 317 are produced by removal of these wax compounds from the raffinate (or converted by catalytic dewaxing or iso-dewaxing). Thereafter the raffinate after removal (or conversion) of the waxy compounds becomes dewaxed oil which is passed to hydrotreating unit 319. In hydrotreating 319, a small volume of naphtha, kerosene, and diesel (along with sulfur in the form of H2S) is generated. However, the majority of the product is passed to fractionation unit 323 where the stream is fractionated in the proper viscosities which are denoted as stream Group II 325. Included in Group II 325 will thus be base oils of different viscosities along with bright stock which has primarily been recovered through the stream called CO-DAO 307 (and prospectively UO-DAO 308), generated by solvent de-asphalting unit 305.
[0056] Turning to FIG. 3 where processing of the UO-VGO is undertaken (versus processing of CO-VGO), UO-VGO is first passed to hydrotreater 319 (upgraded from hydrofinishing). The hydrotreated UO-VGO is then passed as stream 359 to solvent extraction unit 311, thus bypassing solvent dewaxing step 316. (The dewaxing step is preferably not applied because the UO-VGO has been made from used lubricating oils which have already been dewaxed). During a period of time when solvent dewaxing unit 516 is not processing UO-VGO (and thus dewaxing is not otherwise being utilized), an alternative embodiment (not shown) is processing CO-VGO in solvent dewaxing unit 516 and generating wax products and dewaxed oil, with such dewaxed oil being available for processing in other units as have available capacity. Solvent extraction unit 311 then produces two streams, the first of which is unfractionated Groups III and II 367 generated from the raffinate and the second of which is unfractionated Group II 363 generated from the extract. In hydrotreating 319, a small volume of naphtha, kerosene, and diesel (along with sulfur in the form of H2S) is also generated as stream 370. Each of the two unfractionated base oil streams 367 and 363 are then passed to their respective fractionation columns 323 and 373. When processing UO-VGO, fractionation column 323 leads to creation of Group III and Group II base oils labeled as stream 376 and fractionation column 373 leads to creation of Group II base oils 379.
[0057] In the processing mode noted in FIG. 3 above, for a given viscosity, Group II products in stream 367 will most likely be higher VI than Group II products in stream 363, as processed in fractionation columns 323 and 373, respectively. Fractionation columns 323 and 373 may be one and the same units but if so, then these must be run blocked out so that each of the Groups III and II products in raffinate stream 367 and Group II products in extract stream 363 are not commingled during processing. It is thus a preferred mode of operating the invention to disclose a separate fractionation capability for processing the products in streams 367 and 363 simultaneously in separate fractionation columns.
[0058] FIG. 4 presents an alternate configuration in which CO-VGO and UO-VGO may either be run separately or blended in varied proportions (e.g. Blended VGO) and then processed together under a hydrotreating, solvent dewaxing (which could instead be catalytic dewaxing or iso-dewaxing), solvent extraction processing sequence. Running a Blended VGO is depicted by means of a proportional valve (425 in FIG. 4). The function of a proportional valve is to allow either of two alternative feedstocks to be run through the plant individually and exclusively, or to allow for any proportions of the two alternative feedstocks to be combined together and then run through the plant as a blend.
[0059] The assumptions in FIG. 4 are that hydrofinishing is preferably upgraded to hydrotreating, if and as needed the solvent extraction unit has also been upgraded, and an additional fractionation capability may optionally be added so as to provide continuous fractionation of both the higher valued (primarily Group III) stream and the lower valued (Group II) stream. FIG. 4 thus assumes that CO-VGO and UO-VGO will be run through the plant at the same time, but in varied proportions as desired. In FIG. 4, the solid lines represent processing of CO-VGO and the dotted lines represent additional processing associated with the addition of UO-VGO. Unlike in FIG. 3, where UO-VGO is not processed through the dewaxing unit, FIG. 4 depicts processing each of the CO-VGO and UO-VGO, or Blended VGO, through the dewaxing unit. An explanation of processing for the CO-VGO and UO-VGO streams follows next below.
[0060] In FIG. 4, CO-VGO 400 and UO-VGO 450 are charged via proportional valve 425 to hydrotreating unit 419. Also charged to hydrotreating unit 419 is CO-DAO 407 generated by solvent de-asphalting unit 405, which has been generated from vacuum column bottoms CO-VCB 403. Presented as a further option is the separate or blended processing of UO-VCB 404 from which is then generated UO-DAO 408 which is passed to solvent extraction unit 411. Also generated in solvent de-asphalting unit 405 are one or more asphalt-like products shown as CO-Asphalt 409 and UO-Asphalt 410. In hydrotreating 419, a small volume of naphtha, kerosene, and diesel (along with sulfur in the form of H2S) is also generated as stream 470. Because most CO-VGOs contain waxy compounds, after hydrotreating in hydrotreating unit 419, the hydrotreated oil is then passed to solvent dewaxing (which may instead be catalytic dewaxing or iso-dewaxing), whereupon wax products 417 are produced by removal of these wax compounds from the hydrotreated oil (or converted by catalytic dewaxing or iso-dewaxing).
[0061] Following dewaxing in dewaxing unit 416, the dewaxed (and already hydrotreated oil) is then passed to solvent extraction unit 411. The raffinate stream 467 from solvent unit 411 is then passed to fractionation unit 423 where raffinate stream 467 is fractionated in the proper viscosities which are denoted as Groups III and II base oils 476. The extract stream 463 from solvent extraction unit 411 is then passed to fractionation unit 473 where extract stream 463 is fractionated in the proper viscosities which are denoted as Group II base oils 479. Included in either of the heavier streams produced by fractionation units 423 and 473 will be the bright stock which has primarily been recovered through the stream called CO-DAO 407, generated by solvent de-asphalting unit 405. Also included in products produced by fractionation units 423 and 473 will be heavier viscosity base oils which are inherent within CO-VGO which tend to be higher viscosity than the base oils found in most UO-VGOs.
[0062] In the processing mode noted in FIG. 4 above, for a given viscosity, the Group II products in stream 467 will most likely be higher VI than the Group II products in stream 463, as processed in fractionation columns 423 and 473, respectively. Fractionation columns 423 and 473 may be one and the same units but if so, then these must be run blocked out so that each of the Groups III and II products in raffinate stream 467 and Group II products in extract stream 463 are not commingled in processing. It is a preferred mode of operating the invention to disclose a separate fractionation capability for processing the products in streams 467 and 463 simultaneously in separate fractionation columns.
[0063] FIG. 5 presents an alternate configuration in which CO-VGO and UO-VGO may either be run separately, or blended in varied proportions and run as Blended VGO processed together under a solvent extraction, solvent dewaxing (which could instead be catalytic dewaxing or iso-dewaxing), hydrotreating processing sequence. The assumptions in FIG. 5 are that hydrofinishing is preferably upgraded to hydrotreating, and, if and as needed, the solvent extraction unit has also been upgraded. Because each of the CO-VGO and the raffinate and extract streams may be run blocked out, additional fractionation capability may not be required (and FIG. 5 does not show any additional fractionation). The configuration in FIG. 5 allows for Blended VGO to be run through the plant at the same time, but in varied proportions as desired. In FIG. 5, the solid lines represent processing of CO-VGO and the dotted lines represent additional processing associated with the addition of UO-VGO.
[0064] An explanation of processing for the CO-VGO and UO-VGO streams as shown in FIG. 5 follows under three different scenarios. The first scenario is where only CO-VGO is processed. The second scenario is where only UO-VGO is processed. The third scenario is where both CO-VGO and UO-VGO are blended and then processed in some proportions (referred to herein as blended VGO). As noted previously, such flexibility is presented in the present invention by means of a proportional valve. Whenever CO-VGO is run (whether alone or blended), it is assumed that there will be waxy components included in the feedstock and therefore that the process configuration shall preferably include solvent dewaxing (which could instead be catalytic dewaxing or iso-dewaxing).
[0065] In FIG. 5, under the first scenario (CO-VGO only as feedstock), CO-VGO 500 is charged via proportional valve 525 to solvent extraction unit 511, and the extract (which is a low value stream) is then generated as stream 513. Also charged to solvent extraction unit 511 is CO-DAO 507 generated by solvent de-asphalting unit 505, which has been generated from vacuum column bottoms CO-VCB 503. The separate or blended processing of UO-VCB 504 is presented as a further option from which is then generated UO-DAO 508 which is passed to solvent extraction unit 511. One or more asphalt-like products are also generated in solvent de-asphalting unit 505 shown as CO-Asphalt 509 and UO-Asphalt 510. The raffinate from solvent unit 511 is then passed to solvent dewaxing step 516 (which could instead be catalytic dewaxing or iso-dewaxing) whereupon wax products 517 are produced by removal of these wax compounds from the raffinate (or converted by catalytic dewaxing or iso-dewaxing). Thereafter the raffinate after removal (or conversion) of the waxy compounds becomes dewaxed oil which is passed to hydrotreating unit 519. In hydrotreating 519, a small volume of naphtha, kerosene, and diesel (along with sulfur in the form of H2S) is generated. However, the majority of the product is passed to fractionation unit 523 where the stream is fractionated in the proper viscosities which are denoted as stream Group II 579. Included in Group II 579 will thus be base oils of different viscosities along with bright stock which has primarily been recovered through the stream called CO-DAO 507 (and prospectively UO-DAO 508), generated by solvent de-asphalting unit 505.
[0066] In FIG. 5, under the second scenario (UO-VGO only as feedstock), UO-VGO 550 is charged via proportional valve 525 to solvent extraction unit 511, and the extract is then generated as either stream 551 where it is either passed directly to hydrotreating 519, or passed to Intermediate Extract Storage 555 via stream 553. Because the hydrotreater 519 can only run one quality of oil at a time, under the configuration where solvent extraction precedes hydrotreating, only one of the raffinate stream or the extract stream coming from solvent extraction unit 511 can be processed in hydrotreater 519 at once. Thus when either of the raffinate or extract streams is being processed in hydrotreater 519, the other stream must be passed into storage. So, at the same time as the extract is being generated from solvent extraction unit 511, so too is raffinate being generated and this either becomes stream 541 where it is passed directly to hydrotreating 519 or is passed to Intermediate Raffinate Storage 545 via stream 543.
[0067] After raffinate stream 541 is passed directly from solvent extraction unit 511 (or raffinate is passed from Intermediate Raffinate Storage 545), it is then processed in hydrotreater 519 whereupon it becomes Unfractionated Groups III and II 567. Unfractionated Groups III and II 567 is then passed to fractionation unit 523 whereupon it is fractionated into its products by viscosity and becomes Groups III and II Products 576. After extract stream 553 is passed directly from solvent extraction unit 511 (or extract is passed from Intermediate Extract Storage 555), it is then processed in hydrotreater 519 whereupon it becomes Unfractionated Group II 563. Unfractionated Group II 563 is then passed to fractionation unit 523 whereupon it is fractionated into its products by viscosity and becomes Group II Products 579. In each case as the raffinate and extract streams are being processed in hydrotreating 519, a small volume of naphtha, kerosene, and diesel (along with sulfur in the form of H2S) is also generated as stream 570. In the processing mode in FIG. 5 under the second scenario of running UO-VGO only, for a given viscosity, the Group II products in stream 576 will most likely be higher VI than the Group II products in stream 579, even though each will be processed in fractionation column 523 (preferably run blocked out so as not to commingle the higher VI and lower VI base oils together). During a period of time when solvent dewaxing unit 516 is not processing UO-VGO (and thus the dewaxing unit is not otherwise being utilized), in an alternative embodiment (not shown) solvent dewaxing unit 516 processes CO-VGO and generates wax products and dewaxed oil, with such dewaxed oil being available for processing in other units as have available capacity.
[0068] The presentation of scenario 3 in FIG. 5 (Blended VGO) is illustrated by assuming the starting feedstock mix is 100% UO-VGO, but that CO-VGO is increased as a % of the feedstock, and then viewing the preferred mode of operating the invention. As discussed above, when running UO-VGO, the sequence of the solvent extraction unit 511 prior to hydrotreater 519 necessitates the utilization of intermediate storage 545 and 555 as the raffinate and extract must be processed in separate blocks. Also previously noted is how, to save operating expenses, it is preferable to bypass dewaxing unit 516 when processing only UO-VGO. In processing blended VGO by increasing the mix of CO-VGO in UO-VGO, there will reach some point where the waxy compounds included in the CO-VGO will preferably be removed (or converted by catalytic dewaxing or iso-dewaxing) to achieve a targeted low temperature property (such as pour point for example) in the final base oil products. When that point is reached, then the blocked out return lines 547 and 557 will need to connect to dewaxing unit 516 (they are currently depicted as passing to hydrotreater 519). So in running Blended VGO, the unit will again be running blocked out but instead of bypassing the dewaxing unit (as was preferable when running only UO-VGO), processing will still occur blocked out but processing will occur through dewaxing unit 516.
[0069] As the portion of the CO-VGO in the Blended VGO is increased, the ultimate product quality of most of the products produced downstream from hydrotreater 519 and fractionation 523 will degrade, or the yields of the higher product quality will drop, or some combination of the two will occur since the quality of the CO-VGO is less than the quality of the UO-VGO. Because the product quality will drop and/or yields of the higher quality product will drop as the CO-VGO portion of the Blended VGO is increased, and this is a continuum versus a bright line change, running the unit in this mode will require careful balancing of product quality and yield considerations. Achieving variations in the proportions of CO-VGO and UO-VGO has been depicted by means of a proportional valve as presented in FIGS. 4 and 5, but as noted in FIGS. 6A, 6B, and 6C, alternative means of varying proportions may be applied.
[0070] FIGS. 6A, 6B, and 6C depict several means of valve assemblies which enable the two feedstocks to be processed individually or in blended mode through a blending valve (FIG. 6A), gate valves (FIG. 6B), or check valves (FIG. 6C). With the blending valve 605 (FIG. 6A), either of the CO-VGO 600 or UO-VGO 601, or some blend of the two, may be processed passing through to gate valve assembly manifold 607 in which the material may then be passed along any of three different pathways. With reference to FIG. 6B, gate valves 625 and 610 allow either of the CO-VGO 620 or UO-VGO 621, respectively, or some blend of the two, to be processed passing through to gate valve assembly manifold 627 in which the material may then be passed along any of three different pathways. With reference to FIG. 6C, centrifugal pumps 635 and 645 allow either of the CO-VGO 630 or UO-VGO 631, respectively, or some blend of the two, to be processed passing through check valves 640 and 650, respectively, to gate valve assembly manifold 637 in which the material may then be passed along any of three different pathways. Check valves will allow flow in one direction but will prevent backflow so that none of the material which is being pumped by either centrifugal pump 635 or 645 will be passed through to the other pump. Many other configurations for controlling the pathways of the streams may be utilized as may be well understood by one of ordinary expertise in the art.
[0071] In general, a preferred mode of the present invention may be to run CO-VGO and UO-VGO separately and further to run processing of each in the sequence of hydrotreating and then solvent extraction, followed by fractionation, using dewaxing when CO-VGO is being processed in sufficient quantities to generate material amounts of wax products. It is thus also a preferred mode of the current invention that when most or all feedstock being processed is UO-VGO, or CO-VGO which has minimal wax compounds, that the dewaxing unit is bypassed as this will save operating cost and is not expected to result in a material loss of wax product creation. In such times, the dewaxing unit can alternatively be used for processing CO-VGO. It is also possible that processing CO-VGO through the hydrotreater 519 first before dewaxing and solvent extraction may produce benefits in product quality or yield (or reduced operating) cost. In any event, this configuration where hydrotreating precedes solvent extraction, along with the addition of a fractionation column, avoids block treating the raffinate and extract streams separately. In this instance, then, a combination of FIGS. 3 and 4 would then be the preferred mode for processing CO-VGO (but this is not depicted). Many such variations may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of the preferred embodiments that are described in this specification.
[0072] While the present invention has been described by reference to certain of its preferred embodiments, the embodiments presented here are intended to be illustrative rather than limiting in nature and many variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
