What are the requirements for coal fuel in environmentally friendly lime kilns
Environmentally friendly lime kilns have strict quality requirements for coal fuel while pursuing efficient production, to ensure stable calcination process and compliance with environmental standards.
Composition and calorific value requirements: Environmentally friendly lime kilns usually use smokeless coal or high-quality coke as fuel. The fixed carbon content needs to be greater than 78%, and the heat generation needs to be higher than 6500 kcal/kg to ensure the energy required for high-temperature calcination. The ash content should be strictly controlled below 15%. Components such as silica and alumina in ash are prone to form low melting point compounds at high temperatures, which may cause slagging problems in the kiln. The volatile matter should be below 7% to avoid prolonging the combustion process and reducing the calcination efficiency. The sulfur content must be below 1% to reduce the emission of sulfur dioxide from combustion and lower the subsequent desulfurization load.
Physical property requirements: The fuel particle size should be controlled within the range of 1-3 millimeters, and the hardness should be maintained at around level 3 to ensure stable combustion and thermal stability in the kiln. When coal powder is used as an alternative fuel, it needs to meet the 200 mesh fineness standard, as particle size directly affects combustion efficiency and stability. The moisture content of fuel needs to be strictly limited. Excessive moisture will reduce the uniformity of combustion temperature and increase fuel consumption.
Environmental adaptability requirements: The fuel needs to be compatible with environmental protection equipment such as desulfurization, denitrification, and dust removal in lime kilns. By optimizing burner design and oxygen enriched combustion assistance technology, combustion efficiency can be improved and pollutant emissions can be reduced. In practical applications, fuel quality needs to be regularly tested, and coal with ash content greater than 17%, sulfur content greater than 2%, or calorific value less than 6200 kcal should be rejected to ensure lime quality and production cost control from the source.
