Refractories Selection Criteria

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kiln Refractories Selection Criteria

Zoning in cement kiln

  • Drying Zone / Chain Zone
  • Preheating Zone / Calcining Zone
  • Safety Zone
  • Upper and Lower Transition Zone
  • Sintering (Burning) Zone
  • Cooling Zone
Zoning in cement kiln

Zoning in cement kiln

Drying Zone / Chain Zone

  • High abrasion/wear caused by the movement of the chains
  • Low material temperature
    (100-400 °C)
  • Selection of Bricks:

Dense fire-clay

Air setting mortar (water resistant)

Dense, fire-clay castables (if chain hangers requires extensive modification work)

Drying Zone . Chain Zone

Drying Zone . Chain Zone

Preheating Zone / Calcining Zone

  • Preheating Zone: Driven off hydrate-water and heating up of raw material:
    up to 700°C.
  • Calcining Zone: Starts below 600°C and ends at approx. 1200°C. Most part takes place at 700-900°C
  • Mechanical abrasion by material, temperature changes
Preheating Zone . Calcining Zone

Preheating Zone . Calcining Zone

  • Selection of Bricks:

  Preheating Zone

Low alumina fire-clay

Lightweight fire-clay (better thermal insulation)

Calcining Zone

Normal fire-clay

Lightweight fire-clay

Acidic light weight bricks (SiO2 : > 65%) in case of alkali attack

Safety Zone

  • High temperature variations
  • Chemical attack (eutectic reactions)
  • Alkali attack
  • Selection of Bricks:

Low porosity (<16%)

High thermal shock resistance

Basic bricks

Alumina rich bricks:
Al2O3: 50 to 60%

Safety Zone

Safety Zone

Transition Zones

  • Highest thermal load
  • No or only unstable coating
  • Directly exposed to the flame radiation
  • High temperature variations (flame and secondary air)
  • Attack by alkali salts and clinker melts
  • Selection of Bricks:

Magnesia-spinel bricks of very pure (synthetic) materials (chrome free)

Transition Zones

Transition Zones

Sintering (Burning) Zone

  • Material temperature: 1100 °C to 1400 °C (up to 1500 °C)
  • More or less stable coating, formed with clinker and liquid phase.
  • Attack by increased material diffusion with formation of the C3S
  • Attack alkali salts
  • High temperatures (overheating)
  • High thermal shocks depending on coating stability
Sintering (Burning) Zone

Sintering (Burning) Zone

  • Brick Selection

Dolomite

Chrome-free magnesia-spinel

Hands off magnesia-chrome bricks

Cooling Zone

  • High thermal shocks (secondary air temperature, clinker/coating)
  • Abrasion (clinker dust)
  • Alkali attack
  • Overheating
  • Brick Selection

Dense, abrasion resistant high alumina bricks Al2O3 80 %
(with SiC)

Basic bricks (Mg-spinel) in case of heavy chemical attack.

Cooling Zone

Cooling Zone

 

if you have any Questions , please don’t Hesitate to consult our Refractories consult Department at project20062015@gmail.com

 

 

 

 

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Posted in Cement Kiln Refractories, kiln refractories and lining, Maintenance Engineering.

3 Comments

  1. Hi,I check your blog named “Refractories Selection Criteria – Cement Equipment” like every week.Your writing style is witty, keep it up! And you can look our website about

  2. Why particular zone got the name as “Safety zone”? Is it depend on temperature at this location?

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