CO-UTILISATION Co-Utilisation of Gasified Biomass, Refuse and Coal

*• What is the way to reduce emissions of SO_z and CO,?

*•• What did the modification of an existing coal-fired plant in Finland allow?

³-What are the impacts of the innovative technology?

70 Section I. Power Engineering

Despite moves towards greater use of renewable sources to generate power, much of our electricity is still produced from fossil fuel sources, especially coal. One way to reduce emissions of S0₂ and C0₂ is to substitute' some of the coal used by conventional power stations with alternative fuels which produce lesser amounts of gaseous pollutants. This can be technically difficult, but the benefits of success are con­siderable in terms of a cleaner environment and long-term cost-savings ² for the consumer.

The modification of an existing coal-fired plant in Finland allowed 30% of the coal used to be substituted with biomass and refuse-de­rived fuels. Because burning biomass in a conventional power station is difficult and expensive, this has been achieved by installing a gas­ification unit. The gas produced by the gasifier has a very low heat value, especially if a fuel is wet. If, however, this lean gas is mixed with richer gas, produced from coal in the conventional part of the power station, the mixture can be co-combusted, and the need of an expensive fuel dryer is therefore removed. The CFB gasifier at the plant (30 to 70 MW capacity) is complemented by an innovative feed system, which makes it possible to adjust the moisture content of the gas mixture, to ensure optimum combustion conditions in the plant's boiler. The impacts of the innovative technology are al­ready apparent³in a decrease in emissions of C0₂, NO_x, SO_x and particulates. Implementation of similar projects could have a signif­icant impact in the fight against global warming and in making our environment healthier.

1 - заменить; 2 — снижение себестоимости; 3 - очевидный

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