Tuesday, January 7, 2020

What is priming in boiler?


Priming in boiler is the carryover of varying amounts of droplets of water in the steam. It lowers the energy efficiency of the steam and leads to the deposit of salt particles on the super heaters and in the turbines.

Causes of priming in boilers 

  • Improper construction of boiler
  • Excessive ratings
  • Sudden fluctuations in steam demand
  • Impurities in the boiler-water- foaming
  • High level of boiler water
When this boiler water carryover is excessive, steam-carried solids produce turbine blade deposits. These conditions often lead to super heater tube failures. Priming is related to the viscosity of the water and its tendency to foam. These properties are governed by alkalinity, the presence of certain organic substances and by total salinity or TDS. The degree of priming also depends on the design of the boiler and its steaming rate. 

Prevention of priming of boiler

  • Maintain the concentration of solids in the boiler water at reasonably low levels 
  • Avoiding high water levelsAvoid boiler loads 
  • Avoid sudden load changes 
  • Proper boiler design 
  • Very often contaminated condensate returned to the boiler system causes carry-over problems. In these cases the condensate should be temporarily wasted until the source of contamination is found and eliminated.
  • Use anti-foaming and anti-priming agents

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