The Ecotube System

Climate improvement with Ecotubes
Reduced NOx emissions:


The Ecotube System

The Ecotube system represents an innovative cost-effective optimisation tool for combustion processes and principally comprises retractable lances - Ecotubes - that are equipped with injection nozzles. Various agents can be introduced through the nozzles at high pressure and velocity into the furnace media. The Ecotubes are strategically positioned within the furnace enabling the injected agents to create a radically improved mixing of the combustion products, resulting in destruction of laminar gas columns and the formation of completely mixed turbulent flow patterns.

The Ecotube System - Animated video

Ecotube system advantages by comparison with other emission abatement techniques:

• Engineered for retrofit applications
• Lower plant operation costs
• Radically improved turbulence and mixing of combustion gases
• Reduced NOx, CO, SOx, HCl and particles in the flue gas
• Lower stoichiometric ratio (less excess air) in the furnace
• Increased thermal efficiency
• Increased load capacity
• Lower ID fan motor absorbed power
• Reduced boiler-wall metal corrosion
• Reduced erosion of boiler convective surfaces
• Minimum unit down time (3-4 days) needed for installation
• Lower maintenance costs
• No large ducts or furnace modifications required


The first Ecotube System was installed in 1995 and has been installed in Waste to Energy boilers (10-85 MWth), Biomass and Coal boilers (25-270 MWth)

Installation Results:
- 30-90% NOx reduction
- 30-90% CO reduction
- 10-30% reduction of flyash
- 5-10% increased boiler load
- Reduced maintenance costs

Ecotube Experience List

Ecotube-system (One level SNCR)


Ecotube assemblies


Control System


Air supply system


Cooling water system


Injection nozzles

Ecotube-system (Two levels SNCR)

Common combustion problems WITHOUT Ecotubes

Combustion Problem Areas are:

• Poor mixing/laminar flue gas flow
• Uneven temperatures and gas velocities
• Non utilized furnace volumes
• High NOx
• Frequent CO spikes
• High SNCR reagent consumption
• High ammonia slip

Combustion WITHOUT Ecotubes - Animated video

Combustion WITH Ecotubes

Financial Benefits

• Increased waste throughput
• Increased steam flow
• Reduced flue gas flow
• Reduced fly ash carry-over
• Reduced flue gas temperatures in convection pass

Environmental Benefits

• Reduced emissions of NOx, SOx, CO, NH3 and CO2
• Increased residence time in temperatures >850°C
• Radically improved mixing
• Distruction of laminar gas content
• Reduced NOx, CO, SOx, HCL and particles
• Lower stoichiometric ratio possible

Combustion WITH Ecotubes - Animated video

NOx reduction ladder

1. Ecotube Air Staging
2. Ecotube SNCR
3. Ecotube FGR
4. Humidification System

1. Ecotube Air Staging

Significantly improved combustion performance due to improved flue gas mixing etc
NOx, SOx, CO, O2 reduction
Flue gas flow reduction
Increased residence time in temperatures >850°C
Increased boiler efficiency
Fly ash reduction

Read more about Ecotube Air Staging

2. Ecotube SNCR

NOx reduction

Read more about Ecotube SNCR

3. Ecotube FGR

NOx reduction
O2 reduction
Flue gas temperature reduction

Read more about Ecotube FGR

4. Humidification System

Local temperature reduction
NOx reduction
Increased waste throughput
Slagging reduction

5. Traditional SNCR

Read more about Traditional SNCR

With the Ecotube SOx reduction technology a dry sorbent is injected via the Ecotube System into the upper part of the furnace to react with the SO2 in the flue gas.

A finely grained sorbent for example Limestone is distributed quickly and evenly over the entire cross section in the upper part of the furnace in a location where the temperature is in the range of 750-1,250°C. Limestone (CaCO3) or hydrated lime (Ca(OH)2) can be used as sorbent. The sorbent reacts with SO2 and O2 to form CaSO4. This is later captured in a fabric filter or ESP together with unused sorbent and fly ash. As with NOx reduction technology systems, reduction rates ultimately depend on an even distribution of the sorbent in the flue gas in combination with proper mixing together with the flue gases. Reaction times for SOx reduction are 1-2 seconds. The Ecotube SOx reduction technology can be implemented on different boiler elevations to deal with part load conditions.

Removal efficiency is greatly improved compared to traditional wall injection systems due to better mixing and better penetration of the solvent. Fine sorbent particle size and an even distribution of the sorbent over the cross-section of a boiler significantly improves the process performance.