Energy from renewable sources


Energy from renewable sources

Solid: wooden and vegetable biomass
Liquid: bioliquids
Gaseous: synthesis gas from organic sources
Solid: wooden and vegetable biomass
Liquid: bioliquids
Gaseous: synthesis gas from organic sources

Water pipes


The ERTA-WTE water-pipe boiler, has developed from a project which dates back to the 1950s for saturated or superheated steam production with high working pressures. It guarantees continuous operation for 8.000 hours per year without the need of standstills.
It is the ideal solution to be installed downstream of a combustion chamber (adiabatic) of wooden biomass with high dust concentrations in the flue gas. It is also possible to design it with incorporated grate in an absorption combustion chamber.
It is of vertical water-pipe type with natural circulation.
The flue gas flow is vertical both in the radiant as well as in the convection section.
The radiant and convection sections are made of a series of vertical channels containing the platens, the superheater and evaporation benches. These latter sections consist of sub-horizontal pipes and are suitable for the installation of automatic cleaning systems. Suitable doors for the tube bundles inspection are also provided.
Downstream of the generator are installed the economizer’s banks for feed water heating in order to further recover the sensible heat of flue gas and thus increase the overall thermal efficiency.


CAPACITY (MW)) up to 70 up to 70
TEMPERATURE (°C) saturation temperature up to 520
PRESSURE (BARa) up to 100 up to 100



The MT-R series heat generators have been designed for installation downstream of a combustion chamber (adiabatic) of wooden biomass with high dust concentrations in the flue gas.
The design of the radiant chamber and convection tube bundles with vertical flue gas movement, ascending and descending, and the installation of special soot blowers allows a better thermal exchange and prevents soot from being deposited on the tubular surfaces.
The soot is collected in the hoppers under the radiation chamber and the convection tube bundle and automatically discharged through double flap gate valves. It is also possible to install a chain conveyor for the ash collection and transport to a suitable waste container.
The thermo-fluid dynamic characteristics of these generators have been designed to ensure maximum reliability and the highest performance under any load conditions, a regular and long-term operation even in case of heavy duty applications.

To further increase the total efficiency of the whole, it is possible to install downstream of the convection bundle, an economizer and / or an air heater, both also affected by the automatic soot blowing system. For maintenance and cleaning services on the heat generators are provided ladders and platforms for access to the inspection doors.
The construction materials used are high-quality steels and the welding is done with manual and/or automatic technique by skilled personnel. All construction stages are checked by our internal quality control system. The MT-R series boilers are externally insulated with mineral wool panels of suitable thickness and density and covered with corrugated sheets in galvanized steel or aluminium. The steel structures exposed are finished on the surface with a suitable coating treatment. These boilers are supplied complete with all the necessary control, regulation and safety instrumentation.


CAPACITY (MW) from 2 to 35 from 2 to 35 from 2 to 30
TEMPERATURE (°C) up to 100 up to 220 up to 350
PRESSURE (BARa) up to 30 up to 50

Flue gas pipes


The NLS series heat recovery boilers have been designed to be installed downstream of a combustion chamber (adiabatic) of wooden biomass.
The NLS generators can produce hot or superheated water , saturated or superheated steam according to the different configurations.
It is a flue-gas pipes boiler with one or more passes.
The tube bundle is fixed to the plates by means of expanding and welding.
The welding operations of shell and tube plates are performed with automatic submerged arc process; the welds undergo non-destructive testing.
The smoke cases, front and rear, are suitably insulated and equipped with access and inspection doors.
These generators are supplied complete with all the necessary control, regulation and safety devices. In order to obtain a better thermal efficiency it is also possible to install an economizer, made of a series of smooth pipes, at the boiler’s flue gas outlet, suitable to preheat the feed water prior to entering the boiler.
The economizer is provided with inspection doors and is adequately insulated with mineral wool and covered with aluminum sheet.


CAPACITY (MW) up to 10 up to 10 up to 10 up to 10
TEMPERATURE (°C) up to 100 up to 220 up to 220 up to 350
PRESSURE (BARa) up to 30 up to 30 up to 30 up to 30


Mobile grate

The mobile grate is a mechanical grate with hydraulic control. It consists of a series of rows of fixed and mobile bars which are alternately mounted on the supporting frame. Through the movement of the mobile rows, mounted on trolleys and activated by hydraulic cylinders, the fuel is conveyed along the entire surface of the grate up to the waste container.
The grate bars have been designed with specific criteria for the combustion of heterogeneous materials in a wide size, water content and heat value range, such as biomass is. They are provided with suitable nozzles, the dimensions of which vary according to the type of fuel used in order to obtain an even distribution of the combustion air on the grate surface.
The grate bars are made in refractory steel with high chromium content which ensures resistance to flame temperatures and to mechanical dragging abrasions.
In order to best control the combustion process, the grate is divided into different areas where the drying, gasification, combustion and ash extraction phases take place.

Even the combustion air flow is divided into different areas. The amount of combustion air can be differently adjusted in such a way that each combustion stage has the correct percentage of primary combustion air. The secondary air, tertiary air and recirculation gas are introduced by means of suitable injectors directly into the combustion chamber for the completion of the oxidation-reduction process.

Fluidized bed combustion system

The fluidized bed is the best suited mean for efficient and environmental friendly combustion of different solid fuels. The bed material usually consists of quartz sand.
The bed material is kept in suspension by air or recirculated flue gas with such a strength that the adhesion forces are neutralized and the sand particles behave like a liquid. The solid fuel is fed onto this fluidized sand and falls into it. The fuel is partly burnt in the fluidized bed and partly in the freeboard above it.
This combustion system is ideal not only for wooden biomass but also for other solid fuels such as RDF, paper mills pulp, process sludge, plastic, sorted waste, etc.

The system offers the following advantages:

  • Insensitive to fuel size
  • Insensitive to water content in the fuel
  • Insensitive to fine grain particles in the fuel
  • Absence of ash melting
  • Staged and progressive combustion
  • Reliability and long operation life
  • Reduced polluting emissions
  • High combustion efficiency
  • No emergency power supply necessary
  • Load flexibility in the combustion processe
  • Low cost for maintenance and repair

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