Production process of active lime vertical kiln
In the field of lime production, activated lime is widely used in many industries due to its excellent characteristics such as high activity. Activated lime vertical kiln is one of the important equipment for producing activated lime, and its production process has strict requirements and unique procedures.
1、 Raw material preparation stage
Limestone screening
The production of active lime vertical kiln first requires high-quality limestone raw materials. After limestone is extracted from the mine, it needs to be screened to remove impurities and stones that do not meet specifications. Generally, limestone with high calcium carbonate content and low impurities is selected, and the calcium carbonate content is usually required to be above [X]%. By using equipment such as vibrating screens, limestone with particle size that does not meet the requirements is separated to ensure uniform particle size of the limestone entering the kiln. The appropriate particle size range is generally within [specific particle size range], which is beneficial for uniform heating during the calcination process in the kiln.
Raw material storage and transportation
The qualified limestone after screening is transported to the raw material yard for storage. The raw material storage yard should have good ventilation and drainage conditions to prevent limestone from getting damp and deteriorating. When production is required, limestone is transported to the feeding device at the top of the vertical kiln through equipment such as belt conveyors. At the same time, it is necessary to ensure the continuity and stability of the raw material transportation process, and avoid situations such as material breakage that may affect production.
2、 Calcination stage
Preheating inside the kiln
After limestone is added from the top of the vertical kiln, it first enters the preheating zone. In the preheating zone, use the rising hot exhaust gas in the kiln to preheat the limestone. Hot exhaust gas is generated by the combustion of fuel at the bottom of the kiln and flows upwards. During the preheating process, the temperature of the limestone gradually increases, the moisture is evaporated, and at the same time, some impurities in the limestone begin to decompose. The temperature in the preheating zone is generally controlled within the preheating temperature range, which can fully preheat the limestone and prepare it for subsequent calcination.
Calcination reaction
The preheated limestone enters the calcination zone, which is the core process of active lime vertical kiln production. In the calcination zone, fuels (such as coal, natural gas, etc.) are burned under suitable conditions to create a high-temperature environment, and the calcination temperature is generally controlled within [calcination temperature range]. The calcium carbonate in limestone decomposes into calcium oxide (i.e. lime) and carbon dioxide at high temperatures, with the chemical reaction formula CaCO ∝=CaO+CO ₂ ↑. The length of calcination time depends on factors such as the particle size of limestone and the combustion of fuel, and is usually within the range of calcination time. In order to ensure the uniformity and adequacy of calcination, it is necessary to reasonably control the supply of fuel, ventilation, and the distribution of airflow inside the kiln.
cooling
The calcined lime enters the cooling zone. In the cooling zone, lime is cooled by introducing cold air. On the one hand, cooling can lower the temperature of lime, making it easier for subsequent discharge and storage; On the other hand, cold air is heated during the process of cooling lime, forming hot air that can return to the kiln to participate in combustion and heat transfer processes, improving energy utilization efficiency. The cooling time is generally [cooling time range], and the temperature of the cooled lime should be reduced to the appropriate discharge temperature, usually within [discharge temperature range].
3、 Finished product processing stage
Discharge material
The cooled lime is discharged outside the kiln through the discharge device at the bottom of the kiln. The discharge device should ensure the uniformity and stability of the discharge, and prevent blockage and other situations. The discharged lime can be further processed according to different needs, such as crushing, sieving, etc., to meet the requirements of different users for lime particle size.
Quality inspection
Strict quality testing must be conducted on the produced active lime. The main detection indicators include the activity of lime, calcium oxide content, impurity content, etc. Activity is one of the important indicators for measuring the quality of activated lime, and it is generally required that the activity reach [specific activity value] or above. By using chemical analysis and other methods, accurately measure various indicators to ensure that product quality meets relevant standards and user needs. For products that do not meet quality standards, they should be classified or reprocessed.
Storage and transportation
Qualified activated lime products are transported to the finished product warehouse for storage. The finished product warehouse should be kept dry and ventilated to prevent lime from absorbing moisture and deteriorating. During transportation, it is necessary to choose appropriate transportation methods and packaging materials to ensure that lime is not damaged during transportation. For example, transportation can be carried out using sealed packaging bags or specialized transport tankers.
4、 Control and optimization in the production process
temperature control
By installing temperature sensors in different areas of the kiln, real-time monitoring of temperature changes inside the kiln can be achieved. Based on temperature data, adjust parameters such as fuel supply and ventilation to ensure that the temperature in each area of the kiln is within an appropriate range, in order to ensure the quality and efficiency of limestone calcination.
Atmosphere control
The atmosphere inside the kiln also has a significant impact on the calcination process. It is necessary to reasonably control the supply of oxygen, ensure sufficient combustion of fuel, and avoid adverse effects of excessive oxidation or reduction atmosphere on the quality of lime. The control of the kiln atmosphere can be achieved by adjusting the operating parameters of ventilation equipment and burners.
Energy saving and emission reduction measures
In the production process of active lime vertical kiln, attention should be paid to energy conservation and emission reduction. For example, using waste heat recovery technology, the heat in the high-temperature exhaust gas discharged from the kiln is recovered and utilized for preheating combustion air or other production processes; Optimize the combustion system, improve fuel combustion efficiency, reduce exhaust emissions, etc. Through these measures, production costs can be reduced while meeting environmental requirements.
The production process of activated lime vertical kiln is a complex and refined process, from raw material preparation to finished product processing, each link requires strict control and careful operation to produce high-quality activated lime products, meet market demand, and achieve high efficiency, energy conservation, and environmental protection in the production process.
