Processes for viscosity breaking of plastics

Patent metadata

Field	Value
Publication number	US-11802245-B1
Application number	US-202218055986-A
Country	US
Kind code	B1
Filing date	Nov 16, 2022
Priority date	Nov 16, 2022
Publication date	Oct 31, 2023
Grant date	Oct 31, 2023

Abstract

A process for converting solid plastic waste to hydrocarbon oil includes melting a feed comprising solid plastic waste to produce a liquefied plastic stream and visbreaking the liquefied plastic stream in a visbreaker unit having a visbreaker furnace and a soaker vessel. Visbreaking includes heating the liquefied plastic stream in the visbreaker furnace to produce a heated liquefied plastic stream, maintaining the heated liquefied plastic stream at the reaction temperature in the soaker vessel for a residence time to produce a visbreaker effluent, and injecting a stripping gas into the soaker vessel. The stripping gas includes at least one of steam, nitrogen, helium, argon, or combinations of these. The process includes introducing the stripping gas to the liquefied plastic stream upstream of the visbreaker furnace, the heated liquefied plastic stream downstream of the visbreaker furnace, or both. The visbreaker effluent is separated to produce a liquid hydrocarbon oil.

First claim

What is claimed is:

1. A process for converting solid plastic waste, the process comprising:
melting a feed comprising the solid plastic waste to produce a liquefied plastic stream;
visbreaking the liquefied plastic stream in a visbreaker unit comprising a visbreaker furnace and a soaker vessel downstream of the visbreaker furnace, wherein the visbreaking comprises:
heating the liquefied plastic stream in the visbreaker furnace to produce a heated liquefied plastic stream having a temperature at which the plastic undergoes one or more chemical reactions to convert polymer molecules in the liquefied plastic stream to one or more smaller molecules, wherein the heating the liquefied plastic stream to the reaction temperature comprises passing the liquefied plastic stream through the visbreaker furnace comprising a convection section and a radiation section downstream of the convection section;
maintaining a heated liquefied plastic stream at the reaction temperature in the soaker vessel for a residence time to produce a visbreaker effluent; and
injecting a stripping gas into the soaker vessel, where the stripping gas comprises at least one of steam, nitrogen, helium, argon, or combinations of these stripping gases;

introducing the stripping gas to the liquefied plastic stream upstream of the visbreaker furnace, the heated liquefied plastic stream downstream of the visbreaker furnace, or both; and
separating the visbreaker effluent in a visbreaker effluent separation system to yield a product comprising liquid hydrocarbon oil and a lesser boiling effluent.

2. The process of claim 1 , where:
the solid plastic waste comprises chlorine-containing plastics; and
introducing the stripping gas to the liquefied plastic stream, the heated liquefied plastic stream, or both upstream of the soaker vessel increases removal of chlorine from the heated liquefied plastic stream in the soaker vessel and reduces the concentration of chlorine in the liquid hydrocarbon oil.

3. The process of claim 1 , where:
the stripping gas is a dry stripping gas consisting essentially of nitrogen, helium, argon, or combinations of these and maintaining the heated liquefied plastic stream at a reaction temperature of from 300° C. to 400° C. in the soaker vessel causes thermal dechlorination of chloride-containing plastics in the heated liquefied plastic stream, where thermal dechlorination comprises an ionic chain reaction that removes chloride ions from the chloride-containing plastics to produce polyenes and hydrochloric acid; or
the stripping gas comprises steam and maintaining the heated liquefied plastic stream at a reaction temperature of from 300° C. to 400° C. in the soaker vessel causes hydrothermal dechlorination of chloride-containing plastics in the liquefied plastic stream, where hydrothermal dechlorination comprises nucleophilic substitution of chloride ions from in the chloride containing plastics with hydroxyl groups from the steam to produce polyols and hydrochloric acid.

4. The process of claim 1 , where:
the stripping gas comprises steam and an inert gas selected from nitrogen, helium, argon, or combinations of these; and
maintaining the heated liquefied plastic stream at a reaction temperature of from 300° C. to 400° C. in the soaker vessel causes thermal dechlorination and hydrothermal dechlorination of chloride-containing plastics in the heated liquefied plastic stream.

5. The process of claim 1 , where the solid plastic waste in the feed comprises one or more of polyolefins, polystyrenes, polyvinyl chlorides (PVC), polyethylene terephthalate (PET), or combinations of these.

6. The process of claim 1 , comprising passing the liquefied plastic stream into the convection section of the visbreaker furnace by a metering pump, an extruder, or both.

7. The process of claim 1 , where a residence time of the liquefied plastic stream in the convection section of the visbreaker furnace is from 5 minutes to 30 minutes, and a temperature of the heated liquefied plastic stream exiting the convection section of the visbreaker furnace is from 150 degrees Celsius (° C.) to 350 degrees Celsius (° C.).

8. The process of claim 1 , where a residence time of the heated liquefied plastic stream in the radiation section of the visbreaker furnace is from 5 minutes to 30 minutes, and a temperature of the heated liquefied plastic stream exiting the radiation section of the visbreaker furnace is from 250 degrees Celsius (° C.) to 450 degrees Celsius (° C.).

9. The process of claim 1 , comprising introducing the stripping gas between an outlet of the melting vessel and an inlet to the visbreaker furnace, where the temperature of the stripping gas is from 120 degrees Celsius (° C.) to 270 degrees Celsius (° C.).

10. The process of claim 1 , comprising passing the heated liquefied plastic stream from the visbreaker furnace to the soaker vessel, and introducing the stripping gas to the heated liquefied plastic stream between an outlet of the visbreaker furnace and an inlet of the soaker vessel, where the temperature of the stripping gas is from 250 degrees Celsius (° C.) to 350 degrees Celsius (° C.).

11. The process of claim 1 , comprising passing the visbreaker effluent to the visbreaker effluent separation system to produce liquid hydrocarbon oil and a lesser boiling effluent, wherein the visbreaker effluent separation system operates at a separation temperature of less than 450 degrees Celsius (° C.).

12. The process of claim 1 , where the liquid hydrocarbon oil has a chlorine content less than 1000 parts per million by weight based on the total weight of the visbreaker effluent, a kinematic viscosity of 0.1 centistokes (cSt) at 100° C. to 500 cSt at 100° C., or both.

13. The process of claim 1 , comprising:
melting the solid plastic waste in the melting vessel operated at a temperature of from 120 degrees Celsius (° C.) to 270 degrees Celsius (° C.) to produce liquefied plastic stream, where a residence time of the solid plastic waste in the melting vessel is from 1 minute to 120 minutes.
passing melt vessel stripping gas through a liquefied plastic and the solid plastic waste in the melting vessel; and
exhausting a gas stream comprising at least the melt vessel stripping gas and oxygen from the melting vessel, where a flow of the melt vessel stripping gas through the liquefied plastic and the solid waste plastic removes oxygen from the melting vessel and the liquefied plastic in the melting vessel.

14. The process of claim 1 , further comprising contacting the liquid hydrocarbon oil with supercritical water in a supercritical water unit at a pressure of from 22,000 kPa to 30,000 kPa and a temperature of from 374° C. to 600° C., where contacting the liquid hydrocarbon oil with the supercritical water increases the light hydrocarbon content of the liquid hydrocarbon oil to produce a supercritical water unit effluent comprising an upgraded liquid hydrocarbon oil.

15. A process for converting solid plastic waste, the process comprising:
melting a feed comprising the solid plastic waste to produce a liquefied plastic stream;
visbreaking the liquefied plastic stream in a visbreaker unit comprising a visbreaker furnace and a soaker vessel downstream of the visbreaker furnace, wherein the visbreaking comprises:
heating the liquefied plastic stream in the visbreaker furnace to produce a heated liquefied plastic stream having a temperature at which the plastic undergoes one or more chemical reactions to convert polymer molecules in the liquefied plastic stream to one or more smaller molecules;
maintaining a heated liquefied plastic stream at the reaction

Assignees

• Saudi Arabian Oil Co

Inventors

• Choi Ki-Hyouk
• Alabdulhadi Abdullah Tariq
• Lee Joo-Hyeong
• Ahn Young Kyoung
• Yami Abdullah Saleh
• Shahrani Saad Abdullah

Classifications

• B09B2101/77

  containing chlorine · CPC title

• B09B3/80

  involving an extraction step · CPC title

• B09B3/45 Primary

  Steam treatment, e.g. supercritical water gasification or oxidation · CPC title

• C10G9/007

  Visbreaking · CPC title

• C10G55/04

  including at least one thermal cracking step · CPC title