Читать книгу Coal-Fired Power Generation Handbook - James Speight G., James G. Speight - Страница 97

Coal in storage in stockpiles (or in any from when it is exposed to the air) has a tendency to lose heating value and coking quality. In general, high-rank coal (safely stored so as to limit oxidation to a minimum) will lose only about 1% of the heat value per year. On the other hand, improper storage can result in a 3 to 5% loss in the heat value during the first year (Rees et al., 1961).

In addition, the coking characteristics of many coals and coal blends are so seriously affected by aging in storage that they may be totally worthless as a coke oven charge (Landers and Donoven, 1961). However, the data and claims can vary and range from (i) there is no effect on the coking properties after months and years of storage to (ii) there is significant loss of coking properties in as little as one month of storage time. Storage of low-rank coal presents particular problems in that it is usually accompanied by loss of strength, degradation, and some loss of heating value (Jackman, 1957; Mitchell, 1963).