What are the reasons for the high overburning rate of rotary kiln lime kiln
The rotary kiln lime kiln is an important equipment for the thermal decomposition of calcium carbonate to produce calcium oxide, but in the actual production process, the phenomenon of over burning occurs from time to time, that is, the limestone fails to completely decompose or over decompose, resulting in the presence of undissolved calcium carbonate in the generated quicklime or the formation of over burned lime. This phenomenon not only reduces the quality of lime, but also affects the subsequent production process and product application. The following is the cause analysis of the high overburning rate of rotary kiln lime kiln.
Firstly, the particle size of limestone is one of the key factors affecting the calcination effect. If the particle size is too large, the heat is difficult to penetrate into the interior of the stone, resulting in incomplete calcination and green burning; If the particle size is too small, the limestone surface is easy to overheat, the internal carbon dioxide is not fully released, and green burning may also be formed. In addition, uneven particle size distribution will also lead to uneven calcination of materials in the kiln, further increasing the possibility of raw and overburned.
Secondly, the quality of limestone also has an important impact on the calcination effect. Limestone containing more silicon, aluminum, iron and other impurities is easy to form low melting point compounds at high temperatures, leading to nodulation. Nodulation will hinder the normal falling and ventilation of materials, making part of limestone not fully calcined, resulting in green burning; The other part is over calcined due to too long residence time, forming over burnt lime.
Moreover, the selection and proportion of fuel are also important factors affecting the over burning rate. Insufficient fuel or low calorific value, unable to provide enough heat to completely decompose limestone; If there is too much fuel or the calorific value is too high, the combustion temperature may be too high and the burned lime may be formed. In addition, the particle size and moisture of fuel will also affect its combustion effect, and then affect the calcination quality of lime.
The rationality of air supply system is also the key factor affecting the over burning rate. Insufficient air supply or uneven distribution will lead to insufficient fuel combustion, uneven heat transfer, and local green burning or overburning. If the air supply is too strong, the combustion temperature may be too high, accelerating the decomposition rate of limestone and forming over burnt lime.
The design and operation management of kiln body will also affect the over burning rate. The unreasonable design of kiln body, such as the length, diameter and inclination angle of kiln body, will affect the calcination effect and residence time of materials. Improper operation and management, such as uneven distribution of materials and untimely ash unloading, will also lead to uneven distribution of materials in the kiln and affect the calcination effect.
The reasons for the high overburning rate of rotary kiln lime kiln involve many aspects, and corresponding improvement measures should be taken according to the specific reasons to improve the quality and output of lime.
