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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