Plastic pyrolysis heating / reaction method
By employing a multi-stage pyrolysis process with controlled temperature increases and sub-peak maintenance, the method effectively minimizes char formation and maximizes liquid yields from waste plastics, producing valuable pyrolysis products efficiently.
Patent Information
- Application Number
- JP2024541185
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-01-14
- Filing Date
- 2023-01-11
- Publication Date
- 2025-01-24
AI Technical Summary
Existing pyrolysis processes for waste plastics often produce significant amounts of char or coke, leading to undesirable products and inefficiencies.
A method involving multiple heating stages with controlled temperature increases and maintenance at sub-peak temperatures to minimize char formation and maximize liquid yields, including heating waste plastic through a series of zones with defined temperature and time intervals.
This approach achieves high liquid yields with minimal char or coke production, producing valuable pyrolysis products such as pyrolysis oil, naphtha, diesel, and pitch, while reducing energy consumption and reactor complexity.
Smart Images
Figure 2025502124000001_ABST
Abstract
Claims
1. A process for pyrolysis of waste plastics, the process comprising: Heating waste plastic from an initial temperature to a peak pyrolysis temperature in one or more heating stages; providing a heat input sufficient to maintain the temperature of the waste plastic at a pyrolysis reaction temperature below the peak pyrolysis temperature in a final pyrolysis stage, and maintaining the waste plastic at the pyrolysis reaction temperature for a period of time to convert a portion of the waste plastic into pyrolysis products and pitch; recovering the pyrolysis products; and and recovering the pitch.
2. 10. The process of claim 1, wherein the overall conversion of the waste plastics to pyrolysis products is in the range of about 90% to 97% by weight.
3. 2. The process of claim 1, wherein the conversion of the waste plastic to pitch is in the range of about 3% to 10% by weight.
4. 10. The process of claim 1, wherein less than 1% by weight of the waste plastic is converted to coke or char.
5. A process for pyrolysis of waste plastics, the process comprising: heating waste plastic from an initial temperature to a first temperature and maintaining the waste plastic at the first temperature for a first period of time to produce a first heated plastic; heating the first heated plastic to a second temperature and maintaining the first heated plastic at the second temperature for a second period of time to produce a second heated plastic; heating the second heated plastic to a third temperature and maintaining the second heated plastic at the third temperature for a third period of time to produce a third heated plastic; heating the third heated plastic to a fourth peak temperature to produce a fourth heated plastic; providing a heat input sufficient to maintain a temperature of the fourth heated plastic at a fifth temperature and maintaining the fourth heated plastic at the fifth temperature for a fourth period of time; the first temperature is less than the second temperature, the second temperature is less than the third temperature, the third temperature is less than the fourth peak temperature, and the fifth temperature is less than the fourth peak temperature.
6. 6. The process of claim 5, wherein the heating rate in °C / min from the second temperature to the third temperature is less than the heating rate from the third temperature to the fourth peak temperature.
7. 6. The process of claim 5, wherein the heating rate in °C / min from the initial temperature to the first temperature is equal to the heating rate from the first temperature to the second temperature.
8. 6. The process of claim 5, wherein the heating rate in °C / min from the first temperature to the second temperature is equal to the heating rate from the second temperature to the third temperature.
9. 6. The process of claim 5, wherein the first period, the second period, and the fourth period are each longer in duration than the third period.
10. 10. The process of claim 9, wherein a ratio of the third period of time to the second period of time is in the range of 1:10 to 1:
30.
11. 10. The process of claim 9, wherein a ratio of the fourth period of time to the third period of time is in the range of 3:1 to 12:
1.
12. the initial temperature is in the range of 0° C. to 35° C.; the first temperature is in the range of 90° C. to 150° C.; the second temperature is in the range of 250° C. to 350° C.; the third temperature is in the range of about 300° C. to 450° C.; the fourth peak temperature is in the range of 450° C. to 550° C.; The process of claim 5, wherein the fifth temperature is in the range of 400°C to 500°C.
13. heating the third heated plastic to a fourth peak temperature; Heating the third heated plastic to an intermediate temperature at a heating rate of greater than 50° C. / min; and heating the third heated plastic from the intermediate temperature to the fourth peak temperature at a heating rate in the range of 15° C. / min to 30° C. / min.
14. 14. The process of claim 13, wherein heating the third heated plastic to an intermediate temperature at a heating rate of greater than 50°C / min comprises heating the third heated plastic at a rate in the range of 100°C / min to 200°C / min.
15. A process for pyrolysis of waste plastics, the process comprising: heating and melting the waste plastic material in a melting tank to produce molten plastic; transferring the molten plastic from the melt tank to a pyrolysis reactor; heating the molten plastic in the pyrolysis reactor to a peak temperature and then maintaining the temperature of the molten plastic at a reaction temperature below the peak temperature for a period of time; recovering the pyrolysis oil product; and and recovering the pitch.
16. 1. A system for pyrolysis of waste plastics, comprising: a first heating zone configured to heat waste plastic from an initial temperature to a first temperature and maintain the waste plastic at the first temperature for a first period of time to produce a first heated plastic; a second heating zone configured to heat the first heated plastic to a second temperature and maintain the first heated plastic at the second temperature for a second period of time to produce a second heated plastic; a third heating zone configured to heat the second heated plastic to a third temperature and maintain the second heated plastic at the third temperature for a third period of time to produce a third heated plastic; a fourth heating zone configured to heat the third heated plastic to a fourth peak temperature to produce a fourth heated plastic; a fifth heating zone configured to provide sufficient heat input to maintain a temperature of the fourth heated plastic at a fifth temperature less than the fourth peak temperature and to maintain the fourth heated plastic at the fifth temperature for a fourth period of time.
17. 20. The system of claim 16, further comprising a control system configured to control the heat input to each heating zone.
18. 17. The system of claim 16, wherein the fourth heating zone comprises two heating sections including a first heating section configured to provide sufficient heat to heat the third heated plastic at a rate of between 50°C / min and 200°C / min, and a second heating section configured to provide sufficient heat to heat the third heated plastic at a rate of between 15°C / min and 30°C / min.
Citation Information
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