Mechanism Analysis:
Explosion (Bursting) Phenomenon:
- Rapid escape of volatile matter: When the volatile content in petroleum coke is high, as the temperature rises during the initial stage of calcination, the volatile matter escapes rapidly. If the escape rate is too fast, significant steam pressure builds up inside the petroleum coke particles, leading to bursting.
- Improper temperature control: The maximum amount of volatile matter escapes at calcination temperatures between 600–700°C. If the temperature rises too quickly during this stage, the volatile matter escapes violently, exacerbating the bursting phenomenon.
Slagging Phenomenon:
- Incomplete combustion of volatile matter: During the calcination of high-volatile petroleum coke, incomplete combustion of volatile matter produces a large amount of carbon black and unburned particulate matter.
- Ash melting: The ash in petroleum coke melts at high temperatures and combines with unburned particulate matter to form low-melting-point eutectic mixtures that adhere to furnace walls or equipment, leading to slagging.
- Excessive temperature: When the calcination temperature exceeds the softening temperature of the ash, the ash melts and adheres, forming slag.
Preventive Measures:
Control of Calcination Temperature and Heating Rate:
- Segmented heating: During the initial stage of calcination, adopt a lower heating rate to allow the volatile matter to escape slowly, avoiding excessive internal steam pressure. For example, slow heating before 900°C can improve the actual yield.
- Control of high-temperature stage temperature: At high temperatures (e.g., 1240–1300°C), appropriately reduce the heating rate to help improve the true density and oxidation resistance of the calcined coke, reducing the risk of slagging.
Optimization of Calcination Equipment Operation:
- Maintain low material level: In pot furnaces, maintain a low material level to allow the added petroleum coke to quickly expel volatile matter, reducing its residence time in the furnace and lowering the likelihood of slagging.
- Increase negative pressure: Maintain high negative pressure to facilitate the smooth expulsion of volatile matter and prevent its accumulation inside the furnace.
- Regularly clean volatile matter outlets: Frequently clean the volatile matter outlets and collection channels to prevent blockages and ensure unobstructed expulsion of volatile matter.
Adjustment of Raw Material Ratios:
- Mixed calcination: Add low-volatile petroleum coke or calcined coke to high-volatile petroleum coke to reduce the overall volatile content. Ensure accurate ratios and uniform mixing to avoid localized high volatile content.
- Control raw material particle size: Remove oversized materials and metal impurities to reduce inorganic content and minimize slagging sources.
Improvement of Process Parameters:
- Proper control of oxygen content: Maintain an appropriate oxygen content to avoid reducing atmospheres that lower the ash melting point. For example, when the oxygen content is below 5%, the ash melting point decreases by 100–150°C, increasing the risk of slagging.
- Optimize air distribution: Adjust the air distribution ratio according to the calcination stage to ensure complete combustion of volatile matter and reduce the generation of carbon black and unburned particulate matter.
Equipment Modification and Maintenance:
- Modify calcination equipment: For high-volatile petroleum coke, specially modify rotary kilns or pot furnaces, such as by adding volatile matter discharge channels and optimizing internal airflow distribution, to adapt to the calcination requirements of high-volatile materials.
- Regular equipment inspections: Ensure the normal operation of equipment to prevent localized overheating or poor airflow that can lead to slagging. For example, inspect burners and fire channels and promptly clean accumulated ash and slag.
Post time: Apr-14-2026