阅读说明：本技术 热解焦油和闪蒸底部物的改质 (Upgrading pyrolysis tar and flash bottoms ) 是由 徐腾 K·坎德尔 K·J·伊曼纽尔 J·C·叶 G·S·康泰罗 于 2019-05-24 设计创作，主要内容包括：提供了用于共同处理热解焦油与热解前闪蒸底部物的系统和方法。在一些方面,共同处理可对应于溶剂辅助加氢处理。通过组合热解焦油和闪蒸底部物与溶剂,可减小或最小化与馏分的加氢处理有关的各种困难,例如与高粘度进料和/或高硫进料的加氢处理有关的困难。任选地,可使用单独的溶剂和/或稀释剂用于热解焦油和闪蒸底部物。所得改质产物可适合于例如包括在低硫燃油(LSFO)中。(Systems and methods for co-processing pyrolysis tar with pre-pyrolysis flash bottoms are provided. In some aspects, the co-processing may correspond to solvent assisted hydroprocessing. By combining pyrolysis tar and flash bottoms with the solvent, various difficulties associated with hydrotreating of fractions, such as those associated with high viscosity feeds and/or high sulfur feeds, may be reduced or minimized. Optionally, separate solvents and/or diluents may be used for pyrolyzing the tar and flashing the bottoms. The resulting upgraded product may be suitable for inclusion in Low Sulfur Fuel Oil (LSFO), for example.)

1. A process for producing a low sulfur liquid hydrocarbon product comprising:

i) blending a first process stream comprising a tar stream with a working fluid to reduce the viscosity of the first process stream and obtain a second process stream comprising a reduced reactivity, lower viscosity tar;

ii) removing solids from the second process stream to provide a third process stream comprising reduced reactivity, lower viscosity tars substantially free of solids greater than 25 μm in size;

iii) pretreating the third process stream to further reduce the reactivity of the reduced reactivity, lower viscosity tar and obtain a fourth process tar stream;

iv) mixing the pre-pyrolysis flash bottoms stream with at least one of the first, second, third, and fourth process streams to form a mixed stream comprising 10 wt% or more of the flash bottoms stream, the weight ratio of the flash bottoms stream to the tar stream being 1.5 or less, the pre-pyrolysis flash bottoms stream having a T5 distillation point of 400 ℃ or greater;

v) hydrogenating and desulfurizing the fourth process stream and recovering a Total Liquid Product (TLP);

vi) distilling the TLP and recovering a middle fraction and a heavy bottoms fraction of the distillation product, the middle fraction of the distillation product having S_BN100 or greater; and

vii) desulfurizing the heavy bottoms fraction to obtain a low sulfur product having a sulfur content of 1.0 wt.% or less.

2. The method of claim 1, further comprising:

separating from the feedstock a lower boiling fraction having a T95 distillation point of 455 ℃ or less and a first bottoms fraction comprising a pre-pyrolysis flash bottoms stream; and

at least a portion of the lower boiling fraction is pyrolyzed to form at least a pyrolysis tar product, which pyrolysis tar product comprises a tar stream.

3. The process according to claim 1 or claim 2, wherein the pre-pyrolysis flash bottoms stream has S_BNIs 80 or greater; or wherein the pre-pyrolysis flash bottoms stream further comprises a flash bottoms solvent; or wherein the weight ratio of the flash bottoms stream to the tar stream is 1.5 or less; or a combination thereof.

4. The process according to any one of the preceding claims, further comprising recycling a portion of the middle distillate, optionally having S, as at least a portion of the working fluid used in step i)_BNIs 80 or greater.

5. The method of any of the preceding claims, further comprising soaking the tar stream prior to blending the first process stream with the working fluid, wherein the soaking step is performed at a temperature in the range of 200 ℃ to 300 ℃ and at a time in the range of 2 minutes to 30 minutes.

6. The process of any of the preceding claims, wherein the hydrogenating and desulfurizing step v) adds molecular hydrogen of 1000SCF/B to 2000SCF/B on a feed basis to the fourth process stream and reduces the sulfur content of the fourth process stream by 80 wt% to 95 wt%; or wherein the temperature is in the range of 340 ℃ to 410 ℃ and at 0.5hr^-1-1.5hr^-1Hydrogenation and desulfurization step v) at a space velocity (WHSV, feed basis) in the range; or a combination thereof.

7. The process of any of the preceding claims, wherein heavy bottoms desulfurization step vii) provides a product having a sulfur content of 0.2 wt.% or less.

8. The process of any preceding claim, further comprising passing the product of step ii) through a guard reactor prior to step iii) to further remove reactive olefins and residual solids, the guard reactor being at a temperature in the range of from 240 ℃ to 320 ℃ and at 2hr^-1-10hr^-1Operating at a space velocity (WHSV, feed basis) within the range.

9. The process of claim 8, wherein the flash bottoms stream is mixed with at least one of the first process stream, the second process stream, and the third process stream.

10. The process of claim 8 or claim 9, wherein at least one of the catalysts of step v) contains one or more of Co, Ni or Mo; or wherein at least one of the catalysts in the guard reactor contains one or more of Co, Ni or Mo; or wherein the desulfurization step viii) is carried out in a reactor packed with a catalyst containing one or more of Co, Ni or Mo; or a combination thereof.

11. The method according to any one of the preceding claims, wherein at a temperature in the range of 260-300 ℃ and at 1.0hr^-1-4.0hr^-1(iv) carrying out the pre-treatment step (iii) at a feed Weight Hourly Space Velocity (WHSV) in the range.

12. The method of any one of the preceding claims, further comprising blending the low sulfur product with one or more additional fractions to produce an ECA stream comprising the low sulfur product, a low sulfur fuel stream comprising the low sulfur product, or a combination thereof.

13. A process for producing a low sulfur liquid hydrocarbon product comprising:

i) blending the first process stream with a working fluid to reduce the viscosity of the first process stream and obtain a second process stream comprising reduced reactivity, lower viscosity tars;

ii) removing solids from the second process stream to provide a third process stream comprising reduced reactivity, lower viscosity tars substantially free of solids greater than 25 μm in size;

iii) pretreating the third process stream to further reduce the reactivity of the tar and obtain a fourth process tar stream;

iv) hydrogenating and desulfurizing the fourth process stream and recovering a Total Liquid Product (TLP);

v) distilling the TLP and recovering a middle distillate and a heavy bottoms fraction of the distillation product;

vi) mixing at least a portion of the heavy bottoms fraction with a pre-pyrolysis flash bottoms stream to form a mixed feed comprising 25 wt% or more of the heavy bottoms fraction and having a weight ratio of the heavy bottoms fraction to the pre-pyrolysis flash bottoms stream of 0.5 or more, the pre-pyrolysis flash bottoms stream having a T5 distillation point of 400 ℃ or more; and

vii) desulfurizing the mixed feed to obtain a low sulfur product having a sulfur content of about 1.0 wt.% or less.

14. The method of claim 13, further comprising:

separating from the feedstock a lower boiling fraction having a T95 distillation point of 455 ℃ or less and a first bottoms fraction comprising a pre-pyrolysis flash bottoms stream; and

at least a portion of the lower boiling fraction is pyrolyzed to form at least a pyrolysis tar product, which pyrolysis tar product comprises a tar stream.

15. The process according to claim 13 or claim 14, wherein the pre-pyrolysis flash bottoms stream has S_BNIs 80 or greater; or wherein the pre-pyrolysis flash bottoms stream further comprises a flash bottoms solvent; or a combination thereof.

16. The method of any one of claims 13 to 15, further comprising blending the low sulfur product with one or more additional fractions to produce an ECA stream comprising the low sulfur product, a low sulfur fuel stream comprising the low sulfur product, or a combination thereof.

17. The method of any of claims 13-16, further comprising soaking the tar stream prior to blending the first process stream with the working fluid, wherein the soaking step is performed at a temperature in the range of 200 ℃ to 300 ℃ and at a time in the range of 2 minutes to 30 minutes.

18. The process according to any one of claims 13 to 17, wherein the solids removal step ii) comprises centrifugation.

19. The process of any one of claims 13 to 18, further comprising passing the product of step ii) through a guard reactor to further remove reactive olefins and residual solids, the guard reactor being at a temperature in the range of 240 ℃ to 320 ℃ and at 2.0hr, prior to step iii)^-1-10hr^-1Operating at a space velocity (WHSV, feed basis) within the range.

20. The process according to any one of claims 13 to 19, further comprising recycling a portion of the middle distillate as at least a portion of the working fluid used in step i), and wherein from 70 wt% to 85 wt% of the recycled middle distillate is included in the working fluid.

21. The method according to any one of claims 13 to 20, wherein at a temperature in the range of 260-300 ℃ and at 1.0hr^-1-4.0hr^-1(iv) carrying out the pre-treatment step (iii) at a feed Weight Hourly Space Velocity (WHSV) in the range.

22. The process of any one of claims 13 to 21, wherein the hydrogenating and desulfurizing step v) adds molecular hydrogen of 1000SCF/B-2000SCF/B to the fourth process stream on a feed basis and reduces the sulfur content of the fourth process stream by 50 wt% to 95 wt%; or wherein the temperature is in the range of 340 ℃ to 410 ℃ and at 0.5hr^-1-1.5hr^-1Hydrogenation and desulfurization step v) at a space velocity (WHSV, feed basis) in the range; or a combination thereof.

23. The method of any one of claims 13 to 22, wherein at a temperature in the range of 340 ℃ -425 ℃ and at 0.4hr^-1-1.0hr^-1Desulfurization step vii) at a space velocity (WHSV, feed basis) in the range.

24. The process of claim 23 wherein at least one of the catalysts of step v) contains one or more of Co, Ni or Mo; or wherein the desulfurization step viii) is carried out in a reactor packed with a catalyst containing one or more of Co, Ni or Mo; or a combination thereof.

25. The process of any one of claims 13 to 24, further comprising demetallizing the pre-pyrolysis flash bottoms prior to mixing the pre-pyrolysis flash bottoms with at least a portion of the heavy bottoms fraction.

26. A system for producing a low sulfur liquid product, comprising:

a flash separator having a feed inlet, a lower boiling stream outlet, and a flash bottoms outlet;

a steam cracker comprising a steam cracker inlet and a steam cracker outlet, the steam cracker inlet being in fluid communication with the lower boiling point stream outlet;

a first fractionation stage comprising a first fractionation inlet in fluid communication with the steam cracker outlet, one or more first product outlets, and a tar outlet;

at least one soaking vessel and soaking conduit;

a particle separator comprising a particle separator inlet and a particle separator outlet, the particle separator inlet in fluid communication with the tar outlet via at least one of a soaking vessel and a soaking conduit;

one or more first hydroprocessing reactors comprising a first hydroprocessing reactor inlet and a first hydroprocessing reactor outlet, the first hydroprocessing reactor inlet in fluid communication with the particle separator outlet;

a second fractionation stage comprising a second fractionation inlet in fluid communication with the hydrotreater outlet, one or more light products outlets, a middle distillate outlet, and a hydrotreated bottoms outlet; and

one or more second hydroprocessing reactors comprising a second hydrotreater inlet and a second hydrotreater outlet, the second hydrotreater inlet in fluid communication with the hydrotreated bottoms outlet,

wherein at least one of the particle separator inlet and the first hydrotreater inlet is further in fluid communication with the flash bottoms outlet, and

wherein at least one of the particle separator inlet and the first hydrotreater inlet is also in fluid communication with the middle distillate outlet.

27. A system for producing a low sulfur liquid product, comprising:

a flash separator having a feed inlet, a lower boiling stream outlet, and a flash bottoms outlet;

a steam cracker comprising a steam cracker inlet and a steam cracker outlet, the steam cracker inlet being in fluid communication with the lower boiling point stream outlet;

a first fractionation stage comprising a first fractionation inlet in fluid communication with the steam cracker outlet, one or more first product outlets, and a tar outlet;

at least one soaking vessel and soaking conduit;

a particle separator comprising a particle separator inlet and a particle separator outlet, the particle separator inlet in fluid communication with the tar outlet via at least one of a soaking vessel and a soaking conduit;

one or more first hydroprocessing reactors comprising a first hydroprocessing reactor inlet and a first hydroprocessing reactor outlet, the first hydroprocessing reactor inlet in fluid communication with the particle separator outlet;

a second fractionation stage comprising a second fractionation inlet in fluid communication with the hydrotreater outlet, one or more light products outlets, a middle distillate outlet, and a hydrotreated bottoms outlet; and

one or more second hydroprocessing reactors comprising a second hydroprocessor inlet and a second hydroprocessor outlet, the second hydroprocessor inlet in fluid communication with the hydroprocessed bottoms outlet and in fluid communication with the flash bottoms outlet,

wherein at least one of the particle separator inlet and the first hydrotreater inlet is also in fluid communication with the middle distillate outlet.

28. The system of claim 27, further comprising a demetallization reactor, the fluid communication between the second hydrotreater inlet and the flash bottoms outlet comprising indirect fluid communication via the demetallization reactor.

29. A low sulfur liquid product obtained by the process of any one of claims 1 to 25 or produced by the system of any one of claims 26 to 28.

FIELD

The present disclosure relates to processes for upgrading a mixture of pyrolysis tar and flash bottoms fraction to produce a product suitable for blending into a fuel to provide, for example, a low sulfur fuel oil or an emission control zone fuel. The disclosure also relates to apparatus useful for carrying out such methods; products related to such processes, including products comprising treated mixtures and/or upgraded mixtures; and to blends containing such products.

Background

Steam cracking is a form of pyrolysis that can be favored for the production of various small olefins such as ethylene, propylene, and butenes. Such small olefins may then be used in various applications such as polymer synthesis. Due to the value of small olefins, it may be advantageous to use all or a portion of the crude oil as a feedstock for the pyrolysis process. When all or a portion of the crude oil is used as a feed, the product slate from steam cracking and/or other types of pyrolysis can also include naphtha and gas oil fractions.

When a feed comprising heavier components is used as the feed to the pyrolysis process, an initial separation may be performed to separate the feed into a lower boiling fraction (for use in pyrolysis) and a bottoms fraction. Due to the higher boiling point range, the bottoms fraction is generally considered unsuitable for pyrolysis for various reasons such as excessive coke formation and/or low yield of desired olefin products. Some type of flash separator (sometimes referred to as a flash tank) is typically used for separation. The bottoms fraction from the flash separation may be referred to as the flash bottoms fraction. For such flash bottoms produced at or near the beginning of the pyrolysis processing train (train), it was found that high value disposal remains a continuing problem.

In addition to producing the desired olefin and/or other product fractions, one of the byproducts produced during pyrolysis is pyrolysis tar, such as Steam Cracking Tar (SCT) from a steam cracking process. Disposal of Steam Cracked Tar (SCT) has long been a challenge for steam cracking operations. Typical steam cracking processes can be expected to produce several weight percent to 20 weight percent tar. Decades of research have explored various options for upgrading tar to more valuable dispositions and reducing tar yield. For example, tar may be converted to syngas. SCT as a boiler fuel is another relatively high value disposal, but the demand for boiler fuel is limited so that only small amounts of tar can be processed in that manner. Power/electricity generation is also contemplated. The amount of power generated by SCT tar exceeds the power required by the cracker making it necessary to sell electricity to a highly regulated market. SCT has also been proposed as a Carbon Black Feedstock (CBFS), but again there is a concern as to whether CBFS economics can support the use of commercial quantities of tar (e.g., greater than about 550,000 tons/year). In addition, CBFS has a low sulfur specification of about 1 wt%. Because SCT contains significant amounts of sulfur in the steam cracker feed, strict CBFS sulfur specifications result in undesirable limitations on steam cracker feed selection.

Direct blending of tar into fuel oil is also contemplated. Unfortunately, SCT-fuel compatibility issues often result in precipitation of SCT asphaltenes in the blend. While tar can be blended into high sulfur fuel ("HSFO") pools, large amounts of higher value diluents (flux), such as gas oils in a diluent level of 40% or more, are typically required to significantly reduce the SCT viscosity of HSFO blending.

There is therefore a strong commercial drive to find more attractive and ideally more widely applicable SCT dispositions, such as those involving SCT hydroprocessing. For example, SCT hydroconversion has been attempted at typical temperature ranges from 250 ℃ to 380 ℃. Conventional hydroconversion processes using SCT suffer from significant catalyst deactivation due to catalyst fouling. As a result, there remains a need for improved processes for hydroconverting SCT, as well as other tars. It would also be advantageous to identify systems and methods that would allow processing of SCT and flash bottoms from the beginning of a steam cracking process in the same processing train.

U.S. patent application publication No. 2015/0315494 describes a system and method for improving the product properties of a heavy feed steam cracker. The process includes using cavitation to reduce the viscosity of a bottoms stream and/or a steam cracked tar stream from a separator used to produce an input feed to a steam cracker.

U.S. patent No. 7,906,010 describes the use of steam cracked tar and/or bottoms products from a flash drum integrated with a pyrolysis furnace as a blended stream to form fuel oil.

SUMMARY

In various aspects, pyrolysis tar is co-processed with the pre-pyrolysis flash bottoms. The co-processing may be carried out under solvent assisted tar conversion conditions. By combining pyrolysis tar and flash bottoms with the solvent, various difficulties associated with hydrotreating of fractions, such as those associated with high viscosity feeds and/or high sulfur feeds, may be reduced or minimized. Optionally, separate solvents and/or diluents may be used for pyrolyzing the tar and flashing the bottoms. Additionally or alternatively, the co-treatment may correspond to co-treatment of the converted tar product with the flash bottoms prior to pyrolysis. The resulting co-processed product may be suitable for various uses, such as use as a low sulfur fuel blend component or an emission control zone fuel blend component.

In some aspects, the flash bottoms prior to pyrolysis may correspond to a bottoms fraction produced by a separator integrated with the pyrolysis process. Additionally or alternatively, any convenient source of bottoms prior to pyrolysis may be used for co-processing. The co-treatment of the flash bottoms with the pyrolysis tar prior to pyrolysis may allow upgrading of smaller quantities of the bottoms fraction within a refinery unit (setting) without the need for a separate dedicated process train.