The Factors of Lime Kiln Accretion and Its Control Measures

Through comprehensive analysis and research, we find out that the factors of rotary lime kiln accretion are as following:

1. The ash content is on the high side. Although the melting point of coal ash is relative high, coal ash contains large amounts of Si, Al, Fe, which are liable to forming low melting point minerals with CaO, resulting in the formation of the liquid phase, and then leading to rotary lime kiln accretion.

2. Low volatile component in coal ash. It results in slow combustion and overlength black rotor, flame of high temperature shortening, inadequate combustion and low temperature inside the rotary lime kiln. In order to calcine completely, it is likely to increase coal powder amount during production, which to a certain extent cause the high temperature parts to gather, liquid phase increase and finally accretion.

3. Inaccurate control of coal injection quantity. It will brings about unstable combustion in the furnace, local overheating and accretion.

4. The negative pressure in the furnace is too low. It makes the secondary airflow for coal combustion insufficient in amount and velocity, resulting in the high-temperature area concentrating, local liquid phase and accretion.

In order to ensure the continuous and stable running of rotary lime kiln, we mainly focus on the prevention of rotary lime kiln accretion. In general, there are several measures we can take:

1. Strictly control the quality of limestone and coal powder purchased;

2. Add a hot griddle to reduce the ash amount into the rotary kiln;

3. Properly increase the rotate speed of the rotary kiln and promote the heat transfer efficiency, to make the material sufficiently burnt under low temperature;

4. Increase the inlet amount of secondary airflow, draw out the calcining zone, and decrease local high temperature gathering;

5. Reduce coal injection quantity to lower the calcination temperature below 1200 ℃;

6. Improve the blast volume of primary airflow, increase oxygen supply to support coal powder combustion, meanwhile, lengthen the flame and reduce local high temperature.

If we strictly conform to the measures above in the use of rotary kiln, it will achieve an significant effect in solving rotary lime kiln accretion.