Features of lignite:

Lignite, also called brown coal, is the mineral coal with the lowest degree of coalification. It is a low-grade coal with brownish black like the color between peat and pitch coal, and unpolished. As it is rich in vdaf, it is easy to burn and smoke. The woody trace can be seen clearly from the section. The lignite contains humic acid that is soluble in alkali liquor. Its carbon content is 60%~77% and its density is about 1.1~1.2 and volatilization component is more than 40%.
Without thickness of colloidal matter layer, its heat value is about 23.0-27.2 MJ/kg (5500-6500 kilocalorie/kg). its color is brown or brown black with 1.2~1.45 relative density.

Technology of Lignite Dryer:

The previous drying adopts the centrifugal mechanical dehydration method whose equipment is expensive, output is low, and dehydration amplitude is small with 10% dehydration rate once and 15-20% moisture remains. The rotary lignite dryer adopts new technology of breaking and disperse the lignite before drying it by heat which realizes the serialization, industrialization, and automation of drying process. After the lignite drying fabrication processing, the moisture of the wet lignite decreases from 25%-30% to less than 13%. It can be used as fuel coal and has favorable economic, social and environmental benefit after perfecting the coal washing and screening techniques. 

Working Principle of Lignite Dryer:

Rotary lignite dryer adopts low temperature four-stage drying techniques, making the lignite moisture evaporate to less than 13% with the lignite quality being changeless. The first stage drying area removes most moisture at high temperature of 400 centigrade degree on super wet condition to ensure the chemical component of lignite is the same and difficult to burn. The second stage drying area has a room temperature of 400 Celsius degree. Dehydrate by the medium temperature inducing air forcefully to ensure the lignite coking not. The third stage drying area’s room temperature is 120 Celsius degree to 210 Celsius degree. By the crushing plant in the rotary drum, the material is stricken repeatedly, dispersed, and dried in direct flow way. The fourth stage drying is high air exhausting area with room temperature of 60 Celsius degree to 80 Celsius degree. Dehydrate by the negative pressure low temperature hot current in the induced draft system.