Coal has been an important energy source of humanity since the industrial revolution. As an organic solid fuel, its chemical composition, calorific value and other characteristics have an important impact on the use of its thermal energy. The demand for coal in terms of its quality requirements is mainly derived from the fact that gas and thermal power plants are used for power generation.
Generally speaking, the quality requirements for coal used in thermal power plants are as follows:
1.Volatiles: When coal is burned, part of its chemical structure is carried away by the heat, which is the volatile part. Volatile matter affects the calorific value and thermal efficiency of coal, and the volatile matter content is generally below 30%.
2.Ash: Ash is the material that does not turn into gas or liquid after coal is burned, but the formation of the ash affects the adhesion of coal particles and becomes the reason for slagging. The ash content in gas and thermal power generation is usually controlled below 12%.
3.Sulfur content: Coal combustion in thermal power plants will produce sulfur dioxide, which is a pollutant. The sulfur content of coal should be less than 0.8%. If a large amount of sulfur dioxide is produced, the pollution of thermal power plants must be reduced or even eliminated.
4.Martensite content: the content of martensite in coal has a great influence on the hardness of coal, and the martensite should be controlled within the reasonable range.
5.Inhibiting slag adhesion: Slag adhesion is a major problem caused by the use of coal power plants. If the coal quality requirements are not met, it will not only reduce the combustion efficiency, but also increase the waterwall erosion and threaten the security of the power stations.
6.Calorific value: The calorific value of coal is one of the main indicators of the quality of coal. Generally, the higher the calorific value, the better the use effect for power plants.
At present, coal-fired power plants using the worlds best technologies can reach a calorific value of 20000 kcal/kg, which is much higher than the original energy efficiency of traditional small-scale power plants.
The strict requirements for coal mainly come under the severe environmental pressures for coal power plants, and is one of the technical goals sought by power plant design and operation personnel. So far, the requirements of coal quality for gas and thermal power have become higher and higher. The quality of coal supplied to thermal power plants must be strictly tested, and the content of relevant elements must meet the needs of power plants.
