What is the process of vertical lime kiln
The process flow of a vertical lime kiln, including raw material preparation, feeding system, calcination process, discharge cooling, and exhaust gas treatment, is clearly explained to help readers gain a deeper understanding of the working principle of the vertical lime kiln.
Vertical lime kiln, as a common lime production equipment, plays an important role in industrial production. Understanding its process flow is of great significance for improving production efficiency, ensuring product quality, and achieving energy conservation and emission reduction.
1、 Raw material preparation
（1） Selection of Limestone
Selecting high-quality limestone requires high calcium carbonate content, minimal impurities, and uniform particle size. Usually, the calcium carbonate content of limestone should be above 90%, and the particle size should be between 40-80 millimeters.
For example, a certain lime plant selects limestone from nearby mines, and after preliminary screening and crushing, controls its particle size within an appropriate range to ensure the effectiveness of subsequent calcination.
（2） Preparation of fuel
Choose appropriate fuels based on actual conditions, such as coal, natural gas, etc., and ensure that the quality and calorific value of the fuel meet the requirements.
For vertical lime kilns using coal, it is necessary to crush and screen the coal to meet the specified standards for particle size and moisture content.
2、 Loading system
（1） Storage bin
The processed limestone and fuel are stored separately in their respective silos to ensure the supply of raw materials required for continuous production.
The silo is usually made of steel structure, with a certain capacity and anti blocking material design.
（2） Enhance transportation
Transport raw materials from the silo to the feeding port at the top of the kiln through a hoist or conveyor belt.
For example, a common bucket elevator can steadily lift limestone to a high position and accurately feed it into the feeding port.
（3） Uniform fabric
Install a fabric device at the top of the kiln to evenly distribute the raw materials inside the kiln, ensuring the uniformity of calcination.
Some fabric devices use rotary fabric feeders, which can achieve uniform fabric distribution in all directions.
3、 Calcination process
（1） Preheating zone
After the raw materials are added from the top of the kiln, they first enter the preheating zone. In the preheating zone, the raw materials exchange heat with the high-temperature exhaust gas rising inside the kiln, gradually increasing the temperature and causing water evaporation.
At this stage, the temperature of the exhaust gas decreases, achieving initial recovery and utilization of thermal energy.
（2） Calcination zone
The preheated raw materials enter the calcination zone, where they are subjected to high temperatures and undergo decomposition reactions, producing quicklime and carbon dioxide.
The temperature in the calcination zone is usually between 900-1200 degrees Celsius, and the calcination time depends on the properties of the raw materials and the specifications of the kiln.
（3） Cooling zone
The calcined quicklime enters the cooling zone and exchanges heat with the cold air entering from the bottom of the kiln. The temperature of the quicklime decreases and the cold air is heated.
Part of the heated air enters the calcination zone as combustion air, while the other part is discharged through pipelines and can be used for waste heat utilization.
4、 Discharge cooling
（1） Finished product discharge
The calcined quicklime is discharged from the bottom outlet of the kiln.
The discharge device usually adopts a sealed design to prevent air from entering the kiln and affecting the calcination process.
（2） Cooling treatment
The quicklime after discharge can be further cooled by natural cooling or forced air cooling to meet the requirements of subsequent storage and transportation.
For example, using an air-cooled conveyor for rapid cooling of quicklime.
5、 Waste gas treatment
（1） Exhaust gas collection
Set up exhaust gas collection ports at appropriate positions on the kiln body to collect the exhaust gas generated during the calcination process.
The collection system usually includes equipment such as pipelines and fans.
（2） Dust removal treatment
Remove dust particles from exhaust gas through a dust collector to reduce environmental pollution.
Common dust collectors include bag filters and electrostatic precipitators.
（3） Desulfurization and denitrification
For pollutants such as sulfur dioxide and nitrogen oxides in exhaust gas, corresponding desulfurization and denitrification equipment should be used for treatment to meet emission standards.
For example, wet desulfurization and selective catalytic reduction denitrification technologies are used to effectively reduce the pollutant content in exhaust gas.
The process flow of vertical lime kiln is a complex and orderly process, involving multiple links such as raw material preparation, feeding, calcination, discharge cooling, and waste gas treatment. Each link is interrelated and influences each other. Only by strictly controlling the process parameters and operating conditions of each link can the stable operation of the lime kiln be ensured, high-quality quicklime products be produced, and the goals of environmental protection and resource conservation be achieved.
