RH Metal Temp Optimization

RH Metal Temp Optimization

  • Causes of Rh Tube Fail:  
(a) COAL ASH CORROSION FOR TUBING
(b) UNEVEN TEMPERATURE DISTRIBUTION ACROSS THE BOILER


  • COAL ASH CORROSION FOR TUBING: Occurs when the tube metal temperature runs higher than the ash fusion temperature, resulting in a liquid slag deposition that oxidizes the metal at a rate many times the normal 0.001 – 0.002” per year. The tube metal temperature increases as the tube operates, due to the build-up of an internal oxide scale that causes the tube to run hotter to produce the same steam temperature.

  • UNEVEN TEMPERATURE DISTRIBUTION : Leads to rupture of tubes due to creep failure.Another major factor that influences tube life is the creep rupture strength of the material

  • Factors affecting RH Metal Temperature
  • BT Increase-->RH Temp Increase
  • Total Air Flow Increase-->RH Temp Increase
  • PA Flow Increase-->>RH Temp Increase
  • RH Spray Increase--> RH Temp Decrease
  • Mill Combination: Mixed results
  • Fg Temp at RH Inlet Increase-->RH Temp Increase


  • LOW BURNER TILT: Leads to lower HRH(L) and SH(R) temperature.
  • Practice LRSBs in the areas where temperature is lower

  • OPTIMIZED AIR FLOW: Can lead to inadequate combustion
  • Regular checking and maintenance of SADCs and burner tilt to ensure uniform secondary air distribution in furnace leading to proper combustion
  • PRACTISING LRSBs AND SOOT BLOWING ON REGULAR BASIS

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