Understanding False Air in Cement Industry: Causes and Effects

False air in the cement industry refers to unwanted ambient air entering the process system through leaks or openings where no air should enter. This air does not participate in combustion or the process but mixes with hot gases, causing operational and energy problems.

Definition of False Air

False air is defined as air infiltration into process equipment that is not part of the designed airflow. It usually enters due to worn seals, leaks in ducts, inspection doors not sealed, and expansion joints damage.

Common Sources of False Air in Cement Plants

The typical locations where false air enters include:

• Kiln system
• Kiln inlet seal
• Kiln outlet seal
• Burner pipe sealing
• Preheater tower
• Cyclone inspection doors
• Expansion joints
• Flanges and duct connections
• Fans and ducts
• ID fan casing
• Fan shaft seals
• Damaged ducting
• Grinding section
• Raw mill outlet
• Cement mill ducts
• Bag filter casing

Large amounts of false air often enter through kiln inlet and outlet seals due to the kiln rotation and large diameter seals.

Effects of False Air on Cement Process

False air has serious impacts on kiln and mill operation, including:

• Thermal Effects: Decreases gas temperature, increases heat loss, and requires more fuel to maintain temperature.
• Electrical Effects: Higher ID fan power consumption and larger gas volume in the system.
• Production Effects: Reduced kiln capacity, unstable flame, and poor drying in raw mill.
• Mechanical Effects: Higher fan wear, more dust circulation, and difficult material transport.

Even 1% increase in false air can increase exhaust heat loss by ~3 kcal/kg clinker.

Why Process Engineers Care About It

In many plants, 10–20% of kiln gas flow can be false air, which directly increases fuel cost and decreases productivity. Reducing false air is one of the fastest energy-saving improvements in cement plants.

Practical Examples and Solutions

Addressing sealing, duct integrity, and inspection points can deliver quick and measurable gains. In many cases, addressing the kiln seals or preheater and ducting sections can contribute the most to reducing false air in operating plants.

FAQs

• Q: What is false air in the cement industry? A: False air refers to unwanted ambient air entering the process system through leaks or openings where no air should enter.
• Q: What are the common sources of false air in cement plants? A: The typical locations where false air enters include kiln system, kiln inlet seal, kiln outlet seal, burner pipe sealing, preheater tower, cyclone inspection doors, expansion joints, flanges and duct connections, fans and ducts, ID fan casing, fan shaft seals, damaged ducting, grinding section, raw mill outlet, cement mill ducts, and bag filter casing.
• Q: What are the effects of false air on cement process? A: False air has serious impacts on kiln and mill operation, including thermal effects, electrical effects, production effects, and mechanical effects.
• Q: Why do process engineers care about false air? A: In many plants, 10–20% of kiln gas flow can be false air, which directly increases fuel cost and decreases productivity.

Sources

• Source: Emad ALNaser’s LinkedIn post
• Source: Cement Industry
• Source: American Society of Mechanical Engineers (ASME)

Original source: False Air in Cement Industry: Causes and Effects | Emad ALNaser posted on the topic | LinkedIn