One of the principal aims of Wärtsilä’s Power Plants business, is to maintain a high level of expertise in cleaning methods, and to offer a variety of proven emission reduction technologies for different market needs within its product range. Emission reducing methods fall into two main categories: primary and secondary. Primary methods help prevent emissions from occurring in the first place, whereas secondary methods reduce the amount of emissions that do occur.
The use of primary methods is often recommended, as these are effective ways of eliminating the need for additional investments and possible additional environmental loads. In Wärtsilä power plants, the first priority in emissions reduction is to use dry primary methods, which in practice means optimizing the engine, while at the same time guiding the customer in choosing the right quality of fuel. In certain applications, however, where the reduction efficiencies achievable with dry methods are limited, wet primary methods will give the best overall results. In its power plants business, Wärtsilä considers the most potential wet reduction technologies to be the controlled humidification of the combustion air, and the use of water-in-fuel emulsions.
The reduction of nitrogen oxides in BioPower flue gases has been the subject of continuous product development. By staging the injection of combustion air into the boiler, combustion conditions that reduce NOx emission levels to around 60% compared to non-staged injection, are created.
| Typical emissions from a BioPower plant |
| NO2 |
50...70...90...1201 |
mg/MJfuel |
| CO |
100...150 |
mg/MJfuel |
| Particles |
15, 50, 250,5002 |
Mg/m3n, O2 = 6% |
1Value depends on the nitrogen content of the fuel
2Value depends on local emissions regulations
Secondary methods comprise various types of flue gas cleaning methods. Their use, and the need for them, depend very much on the location of the plant, local fuel availability, and on fuel prices. Wärtsilä actively engages in development work with its equipment suppliers, an important element of which is to raise the efficiency of the cleaning equipment in terms of both emissions reduction and cost.
Reduction of emissions to air
Water consumption and wastewater treatment
