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Brief analysis of air leakage in raw meal vertical mills

Introduction: The Critical Role of Vertical Mills in Cement Production

Raw material vertical mills are essential grinding equipment in cement manufacturing, directly impacting production efficiency, energy consumption, and product quality. However, air leakage in vertical mills is a common yet costly issue, leading to:

✔ Higher power consumption (increased fan load)
✔ Reduced mill output (material loss & unstable grinding)
✔ Premature equipment wear (seal & pipe damage)
✔ Inconsistent product fineness (poor grinding performance)

This guide explores root causes of air leakage in vertical roller mills and provides engineered solutions to improve sealing, reduce downtime, and lower operating costs.

I. Major Impacts of Air Leakage in Vertical Roller Mills

1. Increased Energy Consumption

Air leakage causes heat loss, forcing mills to consume extra hot air to maintain temperature.
Higher fan power demand (e.g., circulating fan energy use spikes by 8.6 kWh/t).

2. Reduced Production Capacity

Escaping air carries away raw meal, decreasing mill load and lowering throughput.

3. Accelerated Equipment Wear

Dust ingress from leaks damages roller seals, bearings, and pipelines, increasing maintenance costs.

4. Poor Cement Quality

Uncontrolled airflow disrupts grinding efficiency, causing overly coarse or fine particles.

II. 5 Key Causes of Air Leakage in Vertical Mills

1. Worn or Damaged Seals

Roller seals, feeder seals, and shaft seals degrade over time, creating gaps.

2. Loose Pipe Connections

Poorly fitted ducts between mill & dust collector allow air escape.

3. Inefficient Locking Feeder Design

Segmented wheel feeders with incorrect gaps cause material spillage & pressure loss.

4. Weak Roller Seal Structure

Traditional flat seals lack flexibility, failing under mill vibrations & temperature changes.

5. Flawed Slag Discharge System

Single-flap valves jam easily, while open chutes expose the mill to uncontrolled airflow.

III. Proven Solutions to Stop Vertical Mill Air Leakage

1. Upgrade to High-Performance Seals

✔ Replace standard seals with silicone wave seals for better elasticity & durability.

2. Reinforce Pipe Joints & Flanges

✔ Use high-temp gaskets and torque-check all bolts during maintenance.

3. Install Advanced Locking Feeders

✔ Switch to rotary feeders with adjustable gaps to balance material flow & sealing.

4. Optimize Roller Seal Design

✔ Implement labyrinth seals or pneumatic sealing systems for long-term reliability.

5. Redesign the Slag Discharge Port

✔ Replace flap valves with non-powered material curtain valves that use system pressure for automatic sealing.

IV. Case Study: 4500 t/d Cement Plant Saves 2.58M Yuan/Year

Problem: A TRM53.4 vertical mill suffered severe leaks, causing:

Oxygen levels at kiln tail: 10.3% (vs. ideal 5–7%)
Raw mill power use: 16.5 kWh/t
Low output temp: 45–55°C

Solutions Applied:

Installed wave-type roller seals.
Upgraded to a rotary locking feeder.
Modified slag discharge with pressure-sealed valves.

Results:

✅ Air leakage reduced by 60%
✅ Energy savings: 3.8 kWh/t
✅ Production increased by 12%
✅ Annual cost savings: ¥2.58 million

V. Conclusion: Maximize Mill Performance with Proper Sealing

Air leakage in raw material vertical mills is a complex and critical issue. Enterprises should address this from multiple angles, including design, installation, and maintenance. By optimizing equipment design, enhancing maintenance, and improving sealing effectiveness, companies can effectively reduce air leakage, increase the operational stability of vertical mills, and enhance production efficiency. If you have any questions about improving equipment performance, please feel free to contact us. Darko is here to provide you with professional solutions and support.