Preheater kilns for active lime production

In the rotary kiln with vertical preheater, the calcination of the limestone into the active lime before the preheating process is one of the very important part of all the calcination content of rotary kiln. Because limestone is not possible directly calcination into lime at 900-1000 ° C.

There are many types of different form, but without having the preheating device on the kiln, in varying degrees is also able to calcine with a certain quality of active lime. However, if the active lime is compared with the active lime produced with the preheating device, the most significant difference between the active lime and the physical and chemical indicators of the two will be CO2 (raw heart) too much, low activity and instability, the appearance of the texture and the characteristics of poor performance and so on.

Limestone in vertical preheater, through the exhaust smoke, the action of forces from the rotary kiln of thermal penetration by preheating the bottom up, continue to move down the limestone of the movement, and to receive the heating. From low temperature to high temperature (200 ~ 900 ℃) gradually transformed, heated to the decomposition temperature. And this heat source is mainly dependent on the waste gas from the rotary kiln.

After the limestone enters the preheater, it is first dried by the penetration of the hot air to remove the moisture contained in itself and entrained. With the constant downward movement, the air temperature is getting higher and higher, limestone particles begin to be heated. When the limestone particles are heated to above 800 ℃, the outer surface of the particles will begin to break down reaction. CO2 (gas) began to be gradually separated from CaCO3. Lime particles surface "wear white" phenomenon.

The theoretical results show that the decomposition temperature of CaCO3 is about 870-920 ℃. In the lower part of the vertical preheater, the exhaust gas flow temperature is generally around 950 ℃. This shows that when the limestone particles into the temperature region, in the completion of the preheating heat storage at the same time, the limestone particle surface partial decomposition reaction began to occur. In the rotary kiln with vertical preheater, this preheating heating process generally takes about 120 minutes.

The vertical preheater is used with rotary kiln, make the high temperature air from kiln tail fully utilize, play a role in saving energy and reducing consumption, it’s an energy saving and environment - friendly product.