Читать книгу Coal-Fired Power Generation Handbook - James Speight G., James G. Speight - Страница 100

In addtion to the benefits of having a ready source of coal for the plant, coal stockpiling also presents also some disadvantages, some of which are (i) stacked coal can be uneconomical because of the costs of the stockpiling operation and the maintenance of the stockpiles, (ii) as a result of oxidation, the coking propensity and the calorific value of the coal may be decreased, (iii) oxidation of coal causes an increase in ignition temperature, (iv) if the coal is fragile, it will be fragmented and the percentage of the small particle size material is increased, (v) oxidized coal decreases the performance of washing plants, and (vi) as a result of storage of the coals containing high percentage of methane in closed silos which are not ventilated as required, explosive gas compositions can be formed.

However, the most important of these disadvantages are the fires caused by oxidation and self-ignition of the coal. These fires in stockpiles cause the loss of feedstock to the power plant and the gases formed by the combustion of the coal (as well as any waste material formed, such as mineral ash) can result in harmful effects on the environment (Duzy and Land, 1985, Ökten et al., 1998).