VINCI Environnement

VINCI Environnement

Recycling Household Waste System

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Energy-from-waste (also called waste-to-energy), converts the energy contained in waste into renewable energy:

  • direct thermal energy (with the production of hot water, superheated water or steam) for delivered into a district heating system or for industrial uses
  • electricity, via steam produced in a turbo alternator
  • combined: heat and electricity

In this technology, combustion depends solely on the calorific value of waste in a furnace consisting mainly of a grate, where combustion takes place via the introduction of “primary” air, and a combustion chamber in which the gas released by the combustion is burned by the injection of “secondary” air. Completing the system, a so-called “recovery” boiler transfers the resulting calories to the intended utilisation. Complete combustion of waste produces residues that can in turn be recycled. Once metal particles have been removed, bottom ash is used in roadbuilding, while the metals is recycled in the metals industry.

The roller grate developed by VINCI Environnement can withstand high NCVs without the need for water cooling. Consisting of 6 slow-turning rollers protected from the combustion 50% of the time and continuously cooled by the combustion air via 6 independent air injection zones, this roller grate combines mechanical simplicity with low maintenance costs.

Reliable, efficient technologies for the environment

VINCI Environnement’s technologies are designed to optimise combustion while minimising production of dioxins, the aim being to achieve near-zero atmospheric emissions. Our roller furnace is equipped with parallel flow combustion chamber between the gas and the waste, thereby very significantly reducing nitrogen oxide and carbon monoxide emissions well below the regulatory limits.

Dioxins (Polychlorinated dibenzodioxins or PCDDs) and furans (dibenzo-furans or PCDF) form a group of persistent organic pollutants known generically as dioxins (PCDD-F) due to their closely related chemical structure. Dioxins are first and foremost the by-products of industrial processes, but they can also appear in the course of natural phenomena such as volcanic eruptions or forest fires. They are the by-products of a large number of manufacturing processes, such as chlorine bleaching of paper pulp or the production of certain herbicides and pesticides. The waste treatment industry now deploys leading edge technologies and complies with Europe’s strict legislation controlling the combustion of waste aimed at achieving near-zero emissions.
By way of comparison, a night’s fireworks display emits 6.8g I-TEQ of dioxins (source: naei.org.uk), whereas a 150,000 t/y energy-from-waste installation compliant with the 20 September 2002 ministerial decision (France) emits 0.083g annually.

Continuous technological innovation

The cooling technologies used in VINCI Environnement’s furnace grates are continuously evolving in order to adapt to the changing nature of waste and prolong the life of installations. VINCI Environnement has developed its own water-cooling technology for its original SOGE’O water-cooled stepped grate. This is particularly well-suited to high NCV waste being treated in small and medium-scale installations, as are fairly common in France and some other European countries. Moreover, VINCI Environnement has redesigned its large-capacity grate system with a new water-cooled roller in response to new needs arising from the combustion of waste obtained from selective collection and its pre-treatment.

Energy recovery

Usually, the energy released by the combustion of waste is recovered in a boiler directly integrated into the furnace in order to optimise its recovery performance. This boiler produces superheated steam while at the same time cooling flue gas prior to final treatment. The superheated steam is then converted into electricity via a turbo-alternator. The resulting electricity is used in the installation’s processes and administrative activities. Any surplus (most of the electricity produced) is fed into the public grid.

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