Into how many stages is coal powder combustion divided?

This post was last edited by zgj2405 on 2011-7-7 18:14. It is divided into three stages: 1. The stage before ignition； 2. Combustion stage ； 3. Burnout phase.

The combustion of coal powder in the furnace can be roughly divided into three stages: 1) Preparation before ignition: The period from when the coal powder enters the furnace until ignition occurs is the preparation stage before ignition. During this stage, the moisture in the coal powder evaporates and the volatile components are released, causing the temperature of the coal powder to rise to its ignition temperature; hence it is also known as the drying and volatilization stage, and it is an endothermic process. At this stage, it is the ignition zone inside the furnace. (2) Combustion stage: When the temperature of the coal powder rises to its ignition point and the concentration of the coal powder is appropriate, ignition occurs and the combustion stage begins. The volatile components ignite and burn first, releasing a large amount of heat that directly heats the coke, causing it to burn at high temperatures. This stage is a highly exothermic phase, which is the combustion zone in the furnace. (3) Combustion phase: The small amount of unburned solid carbon continues to burn until it is completely burned out. This stage is carried out under conditions of insufficient oxygen supply, weak gas-powder mixing, and low temperature inside the furnace, and it takes a long time. At this stage, it is the combustion zone in the furnace. The division into these stages is not absolute; they cannot be separated completely, as in fact they are interconnected and occur simultaneously. Furthermore, the duration of each stage is related to the properties of the coal powder, as well as to the structure and operating methods of the boiler equipment.