Process and production system for the preparation of low-carbon olefins from waste materials

By steam cracking the degradation oil of waste plastics and waste rubber under reduced pressure and controlling the temperature range, the problem of coking in the degradation oil was solved, achieving efficient resource utilization and preparation of low-carbon olefins, and improving production efficiency and equipment online rate.

CN117946715BActive Publication Date: 2026-06-12CHINA PETROLEUM & CHEMICAL CORP +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
CHINA PETROLEUM & CHEMICAL CORP
Filing Date
2022-10-27
Publication Date
2026-06-12

AI Technical Summary

Technical Problem

Most of the degradation oil generated by existing pyrolysis technologies for waste plastics and waste rubber is burned as fuel oil, lacking effective resource utilization, and the steam cracking process is prone to coking, resulting in low online rate.

Method used

Under reduced pressure, the degradation oil is vaporized and steam-cracked, and the temperature is controlled within the range of 350-600℃ to reduce coking in the steam cracking furnace tubes, extend the coking cycle in the radiant section, and achieve this by reducing the number of tubes in the convection section mixing heating section and adjusting the temperature.

Benefits of technology

It improved the resource utilization rate of waste plastics and waste rubber, extended the operating cycle of steam pyrolysis furnaces, and increased the yield of low-carbon olefins and the online rate of the unit.

✦ Generated by Eureka AI based on patent content.

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Abstract

The present application relates to the field of low carbon olefin preparation, and discloses a method and a production system for preparing low carbon olefin from waste materials, the method comprising the following steps: (1) subjecting the waste materials to thermal cracking or catalytic cracking to obtain degradation oil; (2) subjecting the degradation oil to steam cracking reaction in a steam cracking furnace to obtain low carbon olefin; wherein the steam cracking furnace comprises a convection section and a radiation section, and the degradation oil is mixed with water vapor and heated to a transverse temperature in the convection section under reduced pressure, and then enters the radiation section to perform steam cracking reaction; the transverse temperature is 350-600 DEG C; wherein the waste materials are waste plastics and / or waste rubber. The degradation oil is obtained by degrading waste plastics or waste rubber through a chemical recycling method, and the obtained degradation oil is vaporized and subjected to steam cracking under reduced pressure, which can reduce coking phenomenon, prolong the coking period of the radiation section, and improve the online rate of the device.
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Claims

1. A method for preparing low-carbon olefins from waste materials, comprising the following steps: (1) The waste materials are subjected to thermal cracking or catalytic cracking to obtain degraded oil; (2) The degradation oil is subjected to steam cracking reaction in a steam cracking furnace to obtain low-carbon olefins; The steam cracking furnace includes a convection section and a radiation section. Under reduced pressure, the degradation oil is mixed with water vapor in the convection section and heated to a cross temperature, and then enters the radiation section for steam cracking reaction; the cross temperature is 350-430℃. The waste materials are waste plastics and / or waste rubber.

2. The method according to claim 1, wherein, The temperature of the steam cracking reaction is 780-850℃; And / or, the pressure reduction conditions include: a pressure of 1-101 kPa, wherein the pressure is an absolute pressure.

3. The method according to claim 2, wherein, The temperature of the steam cracking reaction is 790-820℃; And / or, the pressure reduction conditions include: a pressure of 2-10 kPa, wherein the pressure is an absolute pressure.

4. The method according to claim 1, wherein, The waste plastic is selected from at least one of polyethylene, polypropylene and polystyrene; And / or, the waste rubber comes from at least one of waste tires, waste gloves, and waste sponges.

5. The method according to claim 1, wherein, The catalytic cracking includes: contacting waste materials with a catalytic cracking catalyst under catalytic cracking reaction conditions to obtain degraded oil; And / or, the conditions for the catalytic cracking include: a reaction temperature of 100-500℃, a reaction pressure of 0.1-3MPa, and a waste material mass hourly space velocity of 500-2000 h⁻¹. -1 ; And / or, the conditions for the thermal pyrolysis include: a reaction temperature of 300-700°C and a reaction pressure of 0.1-5 MPa.

6. The method according to claim 1, wherein, The method further includes: preheating the degradation oil in a convection section before mixing water vapor with the degradation oil to obtain preheated degradation oil; And / or, the temperature of the preheated degradation oil is 120-300℃.

7. The method according to claim 6, wherein, The temperature of the preheated degradation oil is 150-250℃.

8. The method according to claim 1, wherein, The temperature of the water vapor is 480-560℃; And / or, the weight ratio of the degradation oil to water vapor is 1-4:

1.

9. The method according to claim 8, wherein, The temperature of the water vapor is 500-540℃; And / or, the weight ratio of the degradation oil to water vapor is 1.5-2.5:

1.

10. The method according to claim 1, wherein, The method further includes: before step (2), the degradation oil is contacted with a hydrogenation catalyst to carry out a hydrogenation reaction to obtain a hydrogenated fraction of the degradation oil, which is then sent to a steam cracking furnace.

11. The method according to claim 10, wherein, The conditions for the hydrogenation reaction include: a reaction temperature of 200-400℃; a reaction pressure of 2-4MPa; and a hydrogen-to-oil ratio of 100-400:

1.

12. The method according to claim 11, wherein, The conditions for the hydrogenation reaction include: a reaction temperature of 250-350℃; a reaction pressure of 2.5-3.5MPa; and a hydrogen-to-oil ratio of 150-350:

1.

13. The method according to claim 1, wherein, The method also includes separating the products after steam cracking to obtain low-carbon olefins.

14. The method according to any one of claims 1-13, wherein, The production system of the method includes a pyrolysis reactor, a steam cracking furnace, and a pressure reducing device connected in sequence. The pyrolysis reactor is used to thermally or catalytically crack waste materials to obtain degraded oil; The steam pyrolysis furnace includes a convection section and a radiation section connected in series; the pressure reducing device is used to provide pressure reducing conditions; The convection section is used to contact the degraded oil with water vapor and heat it to a cross temperature. The number of convection section furnace tubes is sufficient to make the cross temperature range from 350 to 430°C.

15. The method according to claim 14, wherein, The production system also includes a hydrogenation reactor, which is located between the pyrolysis reactor and the steam cracking furnace. The hydrogenation reactor is used to hydrogenate the degradation oil obtained from the pyrolysis reactor before sending it to the steam cracking furnace.

16. The method of claim 14, wherein, The pressure reducing device includes a separation tower, a reflux condenser, and a pressure reducing device connected in series; wherein the separation tower is connected to the steam cracking furnace.