The burner, commonly known as the coal powder burner, is one of the main equipment composing the rotary kiln system. It is a set of burning device for the use of different flues composed of system equipment, with different structures and properties. Generally, the basic basis for the selection of a set of burner device is as follows.

Applicability of the selected energy medium;
Could be matched with the selected calcinations equipment (Rotary Kiln); 
Adjustability to meet the need of burning and calcinations.

For burner device of rotary kiln, it has different characteristics on its structure, property and other aspects according to the difference of the selected fuels. Even though there are various types of burners, the basic feature must be owned is that the flame shape can be formed when the flue erupts from the burner and starts to burn, no matter on what kinds of conditions.

Different burners form the different flame shapes. The reason is that it is required to meet the property of rotary kiln and the needs of calcinated materials to form the needed flame shape. Such as the different flame characteristics such as a long flame, short flame, wide flame, narrow flame, etc.

For this purpose, a basic understanding of the flame concept is also needed when you learn the knowledge of a set of the burner device.

The operation state of the rotary kiln is depended on the working performance of the burner to a great extent. The extent of the material being calcined depends on the temperature of the material. The temperature comes from the heat generated by the fuel calcination and effect of heat transfer. In the heat transfer process, the hot air flow is required to reach the ideal temperature. The temperature of hot air flow depends on the effect of the flame shape, the combustion regime. 

Many factors can affect the shape of the flame. For example, the structure of burner, fuel properties, kiln length, diameter, air distribution, ventilation etc..

The most basic characteristic of flame shape is reflected on its length and width in the process of flame spread. And the ideal position of flame spread usually refers to the best heat exchange position occurred between the material and the flame when the flame is slightly pointing to the surface of material.