Flörsheim-Wicker Biomass Power Plant has been in operation since 2003. Its facilities include timber storage, the boiler and electricity generation and flue gas cleaning facilities.

Boiler with spreader stoker

The plant combusts around 11.2 tonnes of waste timber and non-recyclable timber an hour. The material is combusts using a spreader stoker. The wood chips are conveyed by the rake into a hopper and blown using air from there into the combustion chamber. Smaller parts are already combusts while still hovering. Larger parts fall onto the grate, where they burn out.

Around 55 tonnes of steam are generated an hour. The steam powers a condensing turbine which in turn produces 14 megawatts of electrical output via a generator.

Use of residues and flue gas cleaning

The flue gas cleaning plant undercuts the strict legal threshold values. The decomposition of nitrogen oxides (NOx) takes place in the boiler using the SNCR (selective non-catalytic reduction) process. Dust is initially removed from the flue gas in two parallel cyclones. After this, acidic noxious gases, heavy metals, dioxins and furans are bound by adding calcium hydrates and activated coke and removed together with the remaining dust in a baghouse filter.

The residues resulting from flue gas cleaning are used as backfill in the mining industry. The burnt out grate ash from the combustion chamber is also put to environmentally-sustainable use - as a material for road construction and landscaping.

Waste Timber Categories

The use of waste timber and non-recyclable timber in Germany is governed by the Waste Timber Ordinance. This subdivides the timber into various quality categories. Flörsheim-Wicker Biomass Power Plant uses waste timber in the following categories:

• AI: Untreated waste timber with insubstantial contaminations
• AII: Treated waste timber which is glued, varnished, coated or painted
• AIII: Waste timber with halogen-organic compounds in the coating, but not wood preservers