Enhancing Coal Feeding Systems for Optimal Kiln Performance

For cement plants that do not have advanced coal dosing systems such as Pfister, Coriolis, or Multicore, traditional coal feeding systems still dominate operations. 

These include:

1. Venturi-Based Coal Transfer and Firing System, V1– A successful project.
   
2. FK Pump-Based Coal Transfer and Firing System, F1.
   
3. FK Pump-Based Direct Coal Firing System, FD1 –  Two successful projects.

Challenges in Traditional Coal Feeding Systems

In these setups, coal transport starts when the coal firing bin reaches its lower limit and stops when it reaches the higher limit. However, this method introduces several challenges:

SFM Draft Variation: Sudden coal transport starts and stops create fluctuations in the SFM (Solid Flow Meter) draft, leading to inconsistent feeding.

Bin Pressurization & Flushing: During transport, the coal firing bin gets pressurized, causing erratic coal flushing, which disrupts stable firing. Continuous monitoring and regulating is a headache for operators. 

Consequences:  Quality variations. Less production. Blame-games. Frustrations. 

The most common issue across all these systems is coal feed flushing, which negatively impacts combustion stability and kiln performance. However, this problem can be resolved efficiently and cost-effectively.

Key to Performance Improvement: Continuous Feeding

Essential Requirements

Rotary Air Lock (RAL) Optimization:

The rotor-casing gap must be minimized. Either refurbish the existing RAL or purchase a new one.

Equip the RAL drive with a Variable Frequency Drive (VFD) for precise speed control.

Barrel Screw Modification:

Minimize the screw-barrel gap to ensure consistent coal flow.

In two of my successful cases, a sleeve was inserted inside the barrel to achieve this. In one project, we took a pipe and fitted the ordinary screw and made the barrel screw overnight. Can you believe it? 

Achieving Continuous Feeding

PID-Controlled RAL Speed: The RAL speed should be automatically regulated using PID control based on the coal firing bin level. The entire system remains operational, with only the RAL speed adjusting as needed.

Optimal Bin Level Maintenance: Implementing this approach successfully maintained a stable bin level of 3.4T to 3.6T.

Benefits of These Modifications

Stable SFM Draft – Eliminating draft variations ensures a consistent coal feed rate.

Eliminating Bin Pressurization – Prevents coal flushing and improves combustion stability. No CO generation. Dramatic Quality and Productivity improvement. No Safety hazard. No headache for operators. In short, it's a MAGIC. 

Application Across Other Systems

If your cement plant uses a different system and faces similar issues, the same methodology can be applied to improve performance. The key takeaway is that controlling coal feed effectively leads to improved kiln feed stability, ultimately optimizing clinker production.

If you have any doubts or need further clarification, feel free to reach out.

Remember: Control your coal feed, and you control your kiln feed. Together, they create magic in cement production!