Boiler Damage Reasons | Yasir Arafin

Boiler Damage Reasons

Boiler Damage Reasons
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Industrial boilers are critical to numerous operations, providing the necessary heat and power for various processes. However, boiler failures and damages can lead to substantial downtime, safety hazards, and financial losses. Understanding the primary causes of boiler damage is vital for effective maintenance and prevention. This detailed article examines the key factors contributing to boiler damage and offers insights into mitigating these risks.

Fuel Explosions

Fuel-rich mixtures:

  • High concentrations of unburned fuel can build up
  • Can ignite in explosive manner
  • Occurs when insufficient air is supplied for fuel being burned

Poor oil atomization:

  • Results in incomplete combustion
  • Can lead to unburned oil puddling on furnace floor
  • Requires proper oil tips, temperature, viscosity, and pressure setting

Improper purge:

  • Not investigating cause of burner trips before relighting
  • Not allowing sufficient purge time after oil spills
  • Attempting to relight without clearing unburned gases

Prevention Tips:

  • Use high-quality fuel and ensure proper storage conditions.
  • Regularly inspect and clean burners to prevent clogging and ensure efficient combustion.
Boiler Damage Reasons

Thermal Stress and Overheating

Thermal stress occurs when rapid temperature changes cause uneven expansion or contraction of boiler components. Overheating, often due to low water levels or excessive scaling, exacerbates this problem. These conditions can result in:

  • Cracking of Pressure Components: Repeated cycles of thermal stress weaken metal structures, leading to cracks in boiler tubes and drums.
  • Failure of Welded Joints: Welded areas are particularly vulnerable to thermal fatigue.

Prevention Tips:

  • Use automatic water level controllers to maintain optimal levels.
  • Avoid sudden changes in boiler load and operating temperature.
  • Schedule regular inspections to identify and address early signs of thermal damage.

Low-Water Conditions

Common causes include:

  • Feedwater pump failure
  • Control valve failure
  • Loss of water to deaerator/makeup system
  • Drum level controller failure
  • Controller left in manual position
  • Loss of plant air pressure
  • Safety valve lifting
  • Large sudden changes in steam load

Trip system failures:

  • Disabled trip circuits
  • Inoperative trip switches due to sludge buildup
  • Improper maintenance of low-water safety systems
Boiler Damage Reasons

Poor Water Treatment

Scale and deposit buildup:

  • Creates insulating layer inside tubes
  • Prevents proper heat transfer
  • Can lead to tube overheating and failure
  • Corrosion issues:
  • Inadequate deaeration
  • Improper chemical treatment
  • Oxygen presence in feedwater
  • Improper blowdown procedures

Improper Warm-up

Causes of damage:

  • Rapid temperature changes creating thermal stress
  • Different expansion rates between components
  • Drum warping (“drum humping”)
  • Refractory cracking from trapped moisture
  • Exceeding 100°F per hour temperature rise rate

Impact Damage to Tubes

Sources of damage:

  • Direct impacts from tools or equipment
  • Misaligned sootblowers
  • Wet steam in sootblowing
  • Corrosion in standby conditions
  • Impact at tube-baffle and refractory interfaces

Severe Overfiring

Results in:

  • Refractory overheating
  • Tube erosion
  • Corrosion of furnace walls
  • Steam moisture carryover
  • Higher operating temperatures beyond design limits
  • Increased maintenance costs

Contaminated Feedwater

Common contaminants:

  • Dissolved oxygen
  • Excessive treatment chemicals
  • Oils
  • Metals and chemical compounds
  • Ion exchange resin
  • Acid and caustic contamination
Boiler Damage Reasons

Improper Blowdown Techniques

Issues include:

  • Incorrect continuous blowdown rates
  • Poor timing of bottom blowdowns
  • Failure to maintain proper water chemistry
  • Improper blowdown of water columns
  • Sludge buildup affecting safety devices

Improper Storage

Problems arise from:

  • Fireside corrosion during cold storage
  • Oxygen corrosion during wet storage
  • Improper nitrogen blanketing
  • Inadequate moisture control
  • Poor shutdown procedures

Flame Impingement

Damage occurs due to:

  • Flame washing furnace walls
  • Localized high temperatures
  • Chemical deposits from flame contact
  • Accelerated corrosion with contaminated fuels
  • Internal deposit formation

Pulling a Vacuum

Issues caused by:

  • Cooling without proper venting
  • Steam condensation creating negative pressure
  • Damage to rolled tube seats
  • Design limitations for negative pressure

External Factors

Environmental and operational conditions also contribute to boiler damage. Examples include:

  • Vibration: Continuous vibrations from nearby machinery can loosen connections and damage components.
  • Weather Conditions: Exposure to extreme temperatures or moisture can corrode external surfaces and insulation.

Prevention Tips:

  • Use vibration isolators and ensure proper alignment of nearby equipment.
  • Protect boilers with appropriate insulation and weatherproof coatings.

Reference:

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