Wid Compliant Waste Wood Biomass and Rdf Combustion Plants
We have got WID compliant boilers for the C grade waste wood and SRF combustion: Our WID compliant waste wood gasification boiler manufacturer has over 60-years experience, Works with really low-quality wood, MDF, and chipboard based biomass, and waste wood, SRF combustion is possible together with biomass (80/20% ratio), Waste wood combustion is more than two seconds 850-degree gasification combustion process. (This is important because grate firing struggles to meet two seconds 850-degree combustion), Boiler power range: 8%-100% (During summer months boiler can run nicely with low heat demand and it accelerates nicely when the boiler is already running), If there are power cuts boiler can start itself automatically, Ash handling is wet ash handling and made from acid resting steel, Flue gas dust content within the boiler is only circa 50 mg/nm3, keeping the boiler clean, The boiler needs to be cleaned only once a year as part of its annual maintenance.
- Output: 0,5MWth to 10MWth
- Temperature range: 110-180°C
- Pressure: 4, 6, 10 or 16 bar
- Fuels: Biomass and co-incineration with SRF waste
- Smoke gas channels are acid resting steel.
- When commissioning is finished we can make onsite testings before last payment as our gasification boilers have emission guarantees.
Two-stage WID/IED compliant waste wood gasification combustion is low in nitrogen emissions. In contrast to conventional grate combustion, glowing ember bed is stationary regardless of power output. And the glowing ember bed is so thick (about 80 cm) that all combustion air oxygen is consumed within the ember bed.
In the absence of oxygen more than 90 % of the nitrogen becomes nitrogen molecules (N2). The remaining nitrogen forms the mainly low oxygenated nitrogen compounds N2O and NO. This is ecologically important, because acid rain causing toxic NO2 compound emissions are very low.
The VTT Technical Research Centre of Finland tested two-stage gasification waste wood combustion boiler (540 kW) and found that when chipboard was burnt nitrogen oxide emissions were at the same level as when clean woodchips were burnt in a grate combustion boiler, in spite of the fact that the nitrogen content of chipboard was more than thirty times higher.
At the first stage primary air enters through the grate to the bottom of the thick glowing ember bed and combustion continues within the ember bed as long as there is enough free oxygen and until all the oxygen has become carbon dioxide (O2+C=CO2) The carbon dioxide then reacts with glowing carbon and forms carbon monoxide (CO2+C=2CO).
As the gas rises from the glowing ember bed, it is mixed with secondary air, causing the gas to ignite. The burning gas enters a narrow chamber where tertiary air is blown into the mixture from all sides, and the gas burns completely within a hot combustion chamber lined with firebricks.
The hot gas rises further into an after burning chamber that prolongs combustion and reduces the amount of unburned gases and dust especially when the fuel used is of low quality and high moisture content.
Because the first stage of combustion takes place within the thick ember bed, which acts like an active carbon filter removing almost all fly ash from the gas, only 2 % of the ash formed rises with the flue gas flow.
The remaining 98 % stays in the ember bed and exits from below to the ash conveyor. This means that the flue gas dust content within the boiler is only circa 50 mg/nm3, keeping the WID/IED compliant waste wood boiler clean and the boiler needs to be cleaned only once a year as part of its annual maintenance.
The flue gas dust content of a conventional grate combustion boiler is more than 1000 mg/nm3. This is why such boilers are equipped with compressed air soot cleaning systems, the disadvantage of which is dust discharges that exceed emission requirements and leave an environmental footprint.
In grate combustion boilers the thickness of the glowing ember bed is initially around 30 cm. The grate moves the ember bed so that the whole bed is burned after travelling along the whole length of the grate. The grate’s movement should always be adjusted to the power output of the boiler and the type of fuel used.
In our WID/IED compliant waste wood gasification boilers combustion is not regulated by moving grates. The thick ember bed remains still and the grate moves simply to cut ash from under the ember bed. The regulation of combustion in our WID compliant waste wood gasification boilers is simpler because only the combustion air needs adjusting.
The regulation happens automatically even if the quality, size or moisture content of the fuel changes. Gasification combustion adjusts to the changes in boiler load much faster than grate combustion.
On top of the thick glowing ember bed there are still more than 2 metres of waste wood fuel in the internal silo. In case of a power cut or other disruption, the boiler runs standby and can restart automatically within another 3 days if the problem is fixed.
In a grate combustion boiler even short-term disruptions may cause the thin ember bed to burn down completely and the boiler requires many hours work to start and reach its required output.