Upgrading of pyrolysis tar and flash bottoms

Patent metadata

Field	Value
Publication number	US-11674097-B2
Application number	US-201916972363-A
Country	US
Kind code	B2
Filing date	May 24, 2019
Priority date	Jun 8, 2018
Publication date	Jun 13, 2023
Grant date	Jun 13, 2023

Abstract

Systems and methods are provided for co-processing of pyrolysis tar with pre-pyrolysis flash bottoms. In some aspects, the co-processing can correspond to solvent-assisted hydroprocessing. By combining pyrolysis tar and flash bottoms with a solvent, various difficulties associated with hydroprocessing of the fractions can be reduced or minimized, such as difficulties associated with hydroprocessing of high viscosity feeds and/or high sulfur feeds. Optionally, separate solvents and/or fluxes can be used for the pyrolysis tar and the flash bottoms. The resulting upgraded products can be suitable, for example, for inclusion in low sulfur fuel oils (LSFO).

First claim

The invention claimed is:

1. A process for preparing a low sulfur liquid hydrocarbon product comprising:
i) blending a first process stream comprising a tar stream with a utility fluid to reduce the viscosity of the first process stream and obtain a second process stream comprising reduced reactivity, lower viscosity tar;
ii) removing solids from the second process stream to provide a third process stream comprising a reduced reactivity, lower viscosity tar that is substantially free of solids of size larger than 25 μm;
iii) pretreating the third process stream to further lower the reactivity of the reduced reactivity, lower viscosity tar and obtain a fourth process tar stream;
iv) mixing a pre-pyrolysis flash bottoms stream with at least one of the first process stream, the second process stream, the third process stream, and the fourth process stream to form a mixed stream comprising 10 wt. % or more of the flash bottoms stream, a 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° C. or more;
v) hydrogenating and desulfurizing the fourth process stream and recovering a total liquid product (TLP);
vi) distilling the TLP and recovering a mid-cut of the distillation products and a heavy bottoms fraction, the mid-cut of the distillation products having a S BN of 100 or more; 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 process of claim 1 , further comprising:
separating a lower boiling fraction and a first bottoms fraction from a feedstock, the lower boiling fraction having a T95 distillation point of 455° C. or less, the first bottoms fraction comprising the pre-pyrolysis flash bottoms stream; and
performing pyrolysis on at least a portion of the lower boiling fraction to form at least a pyrolysis tar product, the pyrolysis tar product comprising the tar stream.

3. The process of claim 1 , wherein the pre-pyrolysis flash bottoms stream has a S BN of 80 or more; 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 of claim 1 , further comprising recycling a portion of the mid-cut as at least a portion of the utility fluid used in step i), the mid-cut optionally having a S BN of 80 or more.

5. The process of claim 1 , further comprising heat soaking the tar stream prior to blending the first process stream with the utility fluid, wherein the heat soaking step is performed at a temperature in the range of from 200° C. to 300° C., and for a time in the range of from 2 minutes to 30 minutes.

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

7. The process of claim 1 , wherein the heavy bottoms desulfurizing step vii) provides a product having a sulfur content of 0.2 wt. % or less.

8. The process of claim 1 , further comprising passing the product of step ii) through a guard reactor that further removes reactive olefins and residual solids before step iii), the guard reactor being operated at a temperature in the range of from 240° C. to 320° C. and a space velocity (WHSV, feed basis) in the range of from 2 hr −1 to 10 hr −1 .

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 , 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 desulfurizing step vii) is performed in a reactor packed with a catalyst that contains one or more of Co, Ni, or Mo; or a combination thereof.

11. The process of claim 1 , wherein the pretreating step (iii) is performed at a temperature in the range of from 260° C. to 300° C. and a feed weight hourly space velocity (WHSV) in the range of from of 1.0 hr −1 to 4.0 hr −1 .

12. The process of claim 1 , further comprising blending the low sulfur product with one or more additional fractions to produce an ECA stream that includes the low sulfur product, a low sulfur fuel oil stream that includes the low sulfur product, or a combination thereof.

13. A process for preparing a low sulfur liquid hydrocarbon product comprising:
i) blending a first process stream with a utility fluid to reduce the viscosity of the first process stream and obtain a second process stream comprising reduced reactivity, lower viscosity tar;
ii) removing solids from the second process stream to provide a third process stream comprising a reduced reactivity, lower viscosity tar that is substantially free of solids of size larger than 25 μm;
iii) pretreating the third process stream to further lower 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 mid-cut of the distillation products and a heavy bottoms fraction;
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 heavy bottoms fraction to pre-pyrolysis flash bottoms stream of 0.5 or more, the pre-pyrolysis flash bottoms stream having a T5 distillation point of 400° C. 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 process of claim 13 , further comprising:
separating a lower boiling fraction and a first bottoms fraction from a feedstock, the lower boiling fraction having a T95 distillation point of 455° C. or less, the first bottoms fraction comprising the pre-pyrolysis flash bottoms stream; and
performing pyrolysis on at least a portion of the lower boiling fraction to form at least a pyrolysis tar product, the pyrolysis tar product comprising the tar stream.

15. The process of claim 13 , wherein the pre-pyrolysis flash bottoms stream has a S BN of 80 or more; or wherein the pre-pyrolysis flash bottoms stream further comprises a flash bottoms solvent; or a combination thereof.

16. The process of claim 13 , further comprising blending the low sulfur product with one or more additional fractions to produce an ECA stream that includes the low sulfur product, a low sulfur fuel oil stream that includes the low sulfur product, or a combination thereof.

17. The process of claim 13 , further comprising heat soaking the first process stream prior to blending the first process stream with the utility fluid, wherein the heat soaking step is performed at a temperature in the range of from 200° C. to 300° C., and for a time in the range of from 2 minutes to 30 minutes.

18. The process of claim 13 , wherein the solids removal step ii) includes centrifugation.

19. The process of claim 13 , further co

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Xu Teng
• Kandel Kapil
• Emanuele Krystle J
• Yeh Jeffrey C
• Contello Giovanni S

Classifications

• C10G2300/308

  Gravity, density, e.g. API · CPC title

• C10G2300/4018

  Spatial velocity, e.g. LHSV, WHSV · CPC title

• C10G2300/205

  Metal content · CPC title

• C10G2300/202

  Heteroatoms content, i.e. S, N, O, P · CPC title

• C10L1/04

  essentially based on blends of hydrocarbons · CPC title