Fluidized Bed Plastic Waste Pyrolysis With Melt Extruder

Patent metadata

Field	Value
Publication number	US-2023159834-A1
Application number	US-202117995607-A
Country	US
Kind code	A1
Filing date	Apr 7, 2021
Priority date	Apr 23, 2020
Publication date	May 25, 2023
Grant date	—

Abstract

Systems and methods are provided for conversion of polymers (such as plastic waste) to olefins. The systems and methods can include an initial pyrolysis stage where a plastic feedstock is delivered to the initial pyrolysis stage by one or more melt extruders. The one or more melt extruders can be heated to maintain the plastic feedstock in a liquid state during delivery of the plastic feedstock to the initial pyrolysis stage. This can allow for delivery of the plastic feedstock into the pyrolysis process with a controlled distribution of plastic into the pyrolysis reactor.

First claim

What is claimed is:

1 . A method for producing olefins, comprising:
melting a plastic feedstock comprising plastic particles of at least one polymer in a melt extruder; transferring the melted plastic feedstock from the melt extruder to a pyrolysis reactor; pyrolyzing the transferred plastic feedstock in a fluidized bed of heat transfer particles in the pyrolysis reactor at a temperature of 400° C. or more to form a pyrolysis effluent; cooling the pyrolysis effluent to form a cooled pyrolysis effluent; separating the cooled pyrolysis effluent to form a gas phase fraction and a liquid phase fraction; and performing a second thermal cracking on a) at least a portion of the gas phase fraction, b) at least a portion of the liquid phase fraction, or c) a combination thereof, in a second thermal cracking stage to form an olefin-containing effluent.

2 . The method of claim 1 , wherein the plastic feedstock is melted at a temperature of 150° C. or more.

3 . The method of claim 1 , wherein transferring the melted plastic feedstock comprises transferring the melted plastic feedstock from the melt extruder to the pyrolysis reactor through a transfer conduit.

4 . The method of claim 3 , wherein transferring the melted plastic feedstock from the melt extruder to the pyrolysis reactor comprises extruding the melted plastic feedstock through a die at an interface between the transfer conduit and the pyrolysis reactor.

5 . The method of claim 3 , further comprising heating the transfer conduit to maintain a temperature of the melted plastic feedstock at 150° C. or more.

6 . The method of claim 1 , wherein transferring the melted plastic feedstock comprises transferring a combined feedstock comprising the melted plastic feedstock and a recycled liquid portion of the olefin-containing effluent.

7 . The method of claim 1 , further comprising forming the plastic feedstock by physically processing plastic particles to reduce a median particle size of the plastic particles to 3.0 cm or less.

8 . The method of claim 1 , further comprising forming the plastic particles by physically processing bulk plastic.

9 . The method of claim 1 , further comprising passing the plastic feedstock into the melt extruder using a screw feeder.

10 . The method of claim 1 , wherein the at least a portion of the gas phase fraction comprises a C 5+ portion of the gas phase fraction.

11 . The method of claim 1 , wherein the plastic feedstock further comprises calcium oxide particles.

12 . The method of claim 1 , further comprising:
withdrawing a portion of the heat transfer particles from the pyrolysis reactor; regenerating the withdrawn portion of the heat transfer particles in a regenerator to form heated heat transfer particles; passing at least a portion of the heated heat transfer particles into the pyrolysis reactor.

13 . The method of claim 12 , wherein the heat transfer particles comprise calcium oxide, at least a portion of the calcium oxide being converted to calcium chloride under the pyrolysis conditions.

14 . The method of claim 12 , further comprising passing at least a third portion of the gas phase fraction into the regenerator, the third portion of the gas phase fraction comprising hydrocarbons.

15 . The method of claim 1 , further comprising performing contaminant removal on the gas phase fraction, the at least a portion of the gas phase fraction, or a combination thereof to reduce a concentration of at least one of Cl, N, and Hg in the gas phase fraction, the at least a portion of the gas phase fraction, or a combination thereof.

16 . The method of claim 1 , wherein the second thermal cracking comprises steam cracking.

17 . The method of claim 16 , further comprising separating the liquid phase fraction to form the at least a portion of the liquid phase fraction and a second fraction comprising a higher T50 boiling point than the at least a portion of the liquid phase fraction.

18 . The method of claim 16 , further comprising recycling at least a portion of the second fraction to the pyrolysis reactor.

19 . The method of claim 18 , wherein performing the second thermal cracking on the a) at least a portion of the gas phase fraction, b) at least a portion of the liquid phase fraction, or c) a combination thereof, further comprises performing the second thermal cracking on a liquid steam cracker feedstock.

20 . The method of claim 19 , wherein the liquid steam cracker feedstock is mixed with the a) at least a portion of the gas phase fraction, b) at least a portion of the liquid phase fraction, or c) a combination thereof prior to entering the second thermal cracking stage.

21 . The method of claim 1 , i) wherein the feedstock comprises 0.01 wt % to 10 wt % polyvinyl chloride, polyvinylidine chloride, or a combination thereof; ii) wherein the feedstock comprises 0.01 wt % to 35 wt % polystyrene; iii) wherein the feedstock comprises 0.1 wt % to 1.0 wt % polyamide; or iv) a combination of two or more of i), ii), and ii).

22 . A system for olefin production, comprising:
a physical processing stage for forming a plastic feedstock comprising plastic particles; a melt extruder in fluid communication with the physical processing stage via a transfer conduit; a pyrolysis reactor comprising a pyrolysis inlet and a pyrolysis outlet, the pyrolysis reactor being in fluid communication with the melt extruder at an interface between the transfer conduit and the pyrolysis inlet, the interface comprising an extrusion die; a regenerator in fluid communication with the pyrolysis reactor; a cooling stage in fluid communication with the pyrolysis outlet; a separation stage comprising a separation stage inlet, a gas effluent outlet, and a liquid effluent outlet, the separation stage inlet being in fluid communication with the cooling stage; and a steam cracking reactor comprising a reactor inlet and a reactor outlet, the reactor inlet being in fluid communication with at least one of the gas effluent outlet and the liquid effluent outlet.

23 . The system of claim 22 , further comprising a contaminant removal stage, the reactor inlet being in indirect fluid communication with the gas effluent outlet via the contaminant removal stage.

24 . The system of claim 22 , wherein the regenerator further comprises a regenerator fuel inlet in fluid communication with the contaminant removal stage.

25 . The system of claim 22 , wherein the system further comprises a liquid separation stage, the reactor inlet being in indirect fluid communication with the liquid effluent outlet via the liquid separation stage.

26 . The system of claim 22 , wherein the pyrolysis outlet is in indirect fluid communication with the pyrolysis inlet.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Maduskar Saurabh S
• Reimers Jay L
• Weber Michael W

Classifications

• C10B53/07

  {of solid raw materials consisting} of synthetic polymeric materials, e.g. tyres (recovery or working-up of waste materials of organic macromolecular compounds or compositions based thereon by dry-heat treatment for obtaining partially depolymerised materials C08J11/10; production of liquid hydrocarbon mixtures from rubber or rubber waste C10G1/10) · CPC title

• C10G2300/4081

  Recycling aspects · CPC title

• C10B49/22

  according to the "fluidised bed" technique · CPC title

• C10G2400/20

  C2-C4 olefins · CPC title

• C10G1/002

  in combination with oil conversion- or refining processes · CPC title