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CYMIC boilers - using CFB technology

CYMIC is an advanced circulating fluidized bed (CFB) boiler developed by Valmet. It combines high-efficiency combustion of various solid fuels with low emissions, even when burning fuels with completely different calorific values at the same time.

The wide size range of CYMIC covers boilers from 50 to 1200 MWth.

High fuel flexibility

The main advantage of the CYMIC boiler is its superb fuel flexibility. Most of the over 70 references around the world are multifuel boilers that combust biomasses and fossil fuels in continuously varying proportions. Co-combustion is an environmentally benign method of combining excellent reliability and availability with a great potential to optimize operational costs by allowing several fuel alternatives.

CYMIC boilers offer ideal combustion technology for:

  • Coals and other solid fossil fuels
  • Recovered fuels
  • Biomasses, including fuels derived from agricultural waste streams
  • Any combination of the above-mentioned fuels

Efficient combustion, low emissions and high steam parameters

With CFB technology, the circulating bed material flows together with flue gas through the furnace, after which it is separated from the gas and returned back to the lower part of the furnace with cyclones. This technology provides an even combustion temperature profile, which is optimal for handling a wide variety of fuel properties, such as heating value, moisture, ash content and a number of low melting point ash components. This also ensures low primary emissions with high combustion efficiency and an excellent utilization of additives for sulphur removal and other special purposes.

The key element in the CFB boiler is the cyclone. CYMIC boilers use high-efficiency cylindrical cyclones constructed of membrane walls covered by a light refractory for erosion protection. No hot expansion joints between the furnace and the cyclone are needed.

High steam parameters are possible without severe corrosion, even with recovered fuels, thanks to fluidized bed heat exchangers located in the loop seal.

For recycled fuel combustion, the CYMIC boiler is equipped with a special grid design for effective debris removal and a back pass, including an empty pass and easily replaceable superheaters.