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WTE (Waste to Energy) and Biomass Boilers

Nooter/Eriksen is more than a trusted HRSG manufacturer. We provide comprehensive Grate Combustion Boiler Package for Waste to Energy and Biomass Plants, including all auxiliary equipment. We’ve been trusted to deliver equipment to project sites in 55 countries around the globe for more than 33 years.

WTE (Waste to Energy) and Biomass Boilers

Fuel handling and metering systems, combustion management systems, flue gas treatment systems, ash handling systems, emissions monitoring and control systems, deaerators, boiler feedwater pumps and condensate pumps, chemical dosing and sampling systems, blowdown tanks, and all electrical, instrumentation and boiler controls necessary to operate the boiler safely and efficiently are available.

Nooter/Eriksen custom designs every grate boiler to optimize performance, efficiency and your unique plant layout requirements. We strive to understand your grate boiler needs and provide a solution that works for you.

From the smallest to the largest installations, our natural circulation designs are available in Horizontal or Vertical layouts in capacities up to 150t/h (331 kpph), with steam temperatures from saturated to 565°C (1050°F) and pressures up to 150barg (2,175psig). Units can be bottom or top supported to better serve the project.

Waste to Energy

Vertical Arrangement

Waste to Energy

Horizontal Arrangement

WTE (Waste to Energy) and Biomass Boilers

We specialize in the efficient recovery of energy from the combustion of waste materials (special waste, industrial waste, refused derived fuel and solid urban or municipal waste) and biomass fuels (raw wood, wood chips, agricultural residuals, and so on).

Urban waste incinerator

Paper mill

Wood industry

Self power production


Across the various applications and industries, the combustion challenges are similar: High moisture content of the fuel, toxic chemicals (like chlorides, dioxin), low calorific value of fuels (8000-18000 kJ/kg or 3,400-7,750 BTU/lb) that can lead to flame instability (i.e. high emission levels) and operation at part loads (normally 60-70% of maximum load is the minimum achievable). Nooter/Eriksen engineers are ready to face these challenges to meet your plant needs.

Fuel Feed

When speaking about biomass or waste combustion, an essential parameter is the flame stability. It’s very important to assure safe operating conditions and to reduce the environmental impact in terms of emissions. Nooter/Eriksen has a vast experience in handling a multitude of different fuels.

We can identify a “stability region” considering calorific value of the fuel, fuel mass flow and heat input. It is clear that the operating range of the grate burner is about 65-100%, largely lower than the one of a natural gas burner (10-100 % load operational range).

Balanced draft furnace

A solid fuel combustion chamber has to work under depressurized conditions (operating pressure slightly under atmospheric) in order avoid that combustion products, rich of pollutants, can exit from the boiler; this causes some air to enter the combustion chamber (called “false air”) thus slightly reducing the boiler efficiency.

An induced draft fan, installed at the stack base, will remove the flue gas keeping the desired pressure at the furnace.

Heating surfaces cleaning

The external surfaces of tubes constantly need to be kept clean from ash, removing slagging and fouling deposits, ensuring a good heat transfer.

For boiler burning solid fuels, soot-blowers that inject pressurized air or steam might not always effective, thus other systems could be installed as:

  • Hammering, on header ends, to vibrate tubes;

  • Shot cleaning, for economizers, with horizontal tubes in vertical duct;

  • Acoustic devices;

  • Water spray against the wall tubes.

Flue Gas Treatment and Emission Control

Control of pollutant’s emissions is one of the most important design parameters. Nooter/Eriksen can design and supply the complete emission control system. Main emission parameters to be controlled are:

  • NOx – CO, unburned carbon and organic carbon

  • SO2 –SO3

  • Dioxin (particularly dangerous)

  • Dust (PM)

High content of organic nitrogen may produce high level of NOx. Injection of ammonia (NH3) or Urea at the end of the furnace shall reduce NOx at high temperature, typically 900-1000 °C (1650-1830°F), utilizing a Selective Non Catalytic Reactor (SNCR). Depending on NOx and SOx level required, also a Selective Catalytic Reactor (SCR) can be installed at low flue gas temperature i.e. 350-300 °C (660-570°F).

CO and unburned carbon can be reduced by optimizing combustion process. Besides that, activated carbon filter can be installed particularly for organic carbon reduction and HCl, HF.

Dioxins are formed at medium temperatures during combustion process and are destroyed at high temperatures: Nooter/Eriksen design guarantees the required residence time inside combustion chamber to eliminate Dioxins (more than 2 seconds). When required a natural gas post-firing burner will be installed at the bottom of the combustion chamber to maintain the furnace outlet temperature higher than 900°C (1650°F).

Dust and particulate content are extremely significant and must be reduced before fuel gas exits the main stack. This is accomplished installing in the flue gas path the following devices:

  • Cyclones

  • Electrostatic Precipitator

  • Fabric filter

  • Scrubber

Auxiliary Equipment

Nooter/Eriksen can, through a sister company or with a subcontractor, perform turn-key installation inclusive of commissioning and startup activities, thus providing a single point of responsibility from design/layout to startup. Nooter/Eriksen guarantees the proper coordination between equipment interfaces and our Aftermarket Services team will support project installations around the world and can handle any upgrade, enhancement, replacement or repair, even for boilers built by other manufacturers.

Nooter/Eriksen scope of supply can include the following equipment/auxiliaries:

  • Fuel Handling

  • Combustion Grate and Ultra Low NOx Burners with Flue Gas Recirculation

  • Radiant, convective sections and economizers

  • Supporting structure with anchor bolts

  • Ash Handling

  • Heating surface cleaning systems

  • Flue Gas Treatment Complete System (Cyclones, Bag Filters, Catalyst systems for CO and NOx control)

  • Continuous emissions monitoring systems (CEMS)

  • Steam sampling and chemical dosing systems

  • Piping, supports, trim and instrumentation

  • Feedwater pumps

  • Forced draft fans with motor and steam turbine drives

  • Deaerator systems and blow down systems

  • Air inlet preheaters

  • Noise attenuation systems (stack and vent silencing, casing thickness, acoustic shroud and/or noise barrier)

  • Ancillaries (Electrical power and control cabling, conduit and raceways, Instrument tubing, Electric lower drum heating coils, heat tracing, lighting, Lightning protection systems

  • External insulation


Nooter/Eriksen has 44 reference for these kind of boilers installed in several countries.

  • Urban Waste: 15

  • Industrial Waste: 6

  • Waste Heat Boilers: 15

  • Biomass: 8