Air- and water-cooled reciprocating step grate - FlexSol

Most modern power plants for the production of energy from waste (EfW) use the proven technology of heat treatment on mixed municipal waste, RDF and SRF. Air- and water-cooled combustion grates and tailor-made boilers, which are manufactured in our European facilities, are the core components of most current EfW plants.

We have more than 20 years of experience in waste incinerator boiler projects across central, western, and northern Europe – design, procurement of materials, production, transport, assembly, and commissioning.

Designed with a solid metal construction, the combustion grate can be built horizontally or/and as inclined reciprocating grate. Our specialty is designing natural water/steam boiler circulation, which increases boiler operation availability and lifetime while decreasing maintenance. We base our design on calculations, experience, and engineering best practices.

The grate bars can be cooled with water-cooling circuit, air-cooling, water-cooling circuit and air-cooling combined, depending on the fuel's lower heating value. The thermal and mechanical stress of the grate bars is greatly reduced thanks to the right choice of media cooling circuit.

Choosing the right cooling media reduces thermal and mechanical stress on the grate bars, increasing boiler availability and reducing maintenance costs. For fuels with a high LHV - lower heating value, we use water to cool the grate bars, and the heat from the cooling water can be used to heat the combustion air. This returns heat to the boiler, increasing efficiency and reducing electric power and fuel consumption.

By heating the combustion air, we also have a positive effect on flue gas emissions. The primary air outlet openings are self-cleaning and can be adjusted according to the fuel.


Our boiler design reduces flue gas emissions and treatment costs while minimizing energy consumption for cleaning surfaces, thus increasing efficiency and availability without the need for manual cleaning.

We choose high-quality materials and use the right boiler design to decrease the likelihood of corrosion, high-temperature corrosion, erosion, and increase the boiler's lifetime when handling aggressive fuels such as those with high ash content, and high levels of aggressive chemicals like chlorine, sulfur, and fluorine.

We continuously improve our boiler design to increase steam parameters, such as pressure and temperature, which have a positive effect on the overall efficiency of industrial processes in power plants, chemical plants, co-generation plants, and other industrial facilities.


  • Minimal fuel loses
  • Low operating costs
  • High level of automatization

Optimum fuel/air ratio:

  • Reduced flue gas flow
  • Low operating costs for SNCR stage
  • Low operating costs for electrical power and auxiliary systems
  • High efficiency of the entire system

Air-cooled combustion grate (6-14 Mj/kg)

  • Biomass
  • Waste

Water-cooled combustion grate (7-30 Mj/kg)

  • Biomass
  • Municipal waste
  • RDF, SRF
  • Chemical hazard
  • Industrial waste

ANDRITZ power plant service experts work in close cooperation with customers to improve the safety, performance, stability, availability, and efficiency of power generation equipment. ANDRITZ is well-positioned to offer the full support our customers need.

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35000 Slavonski Brod
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