How to improve the calcination efficiency of lime vertical kiln equipment
As the main equipment for producing quicklime, the calcination efficiency of lime vertical kiln directly affects product quality, energy consumption level, and enterprise economic benefits. Improving calcination efficiency requires comprehensive optimization from multiple aspects such as kiln structure, raw material control, combustion system, and thermal management.
1. Optimize kiln structure and operating parameters
The aspect ratio and lining design of a vertical kiln directly affect the material retention time and heat exchange efficiency. Appropriately increasing the height of the kiln body can prolong the calcination time, but excessive height can lead to increased airflow resistance; Reasonable lining (such as high alumina refractory bricks) can reduce heat loss and improve insulation performance. In addition, controlling the temperature of the calcination zone (usually 1050-1150 ℃) and the airflow velocity to avoid local overburning or undercorning is the key to ensuring the complete decomposition of limestone.
2. Strict raw material screening and particle size control
The purity (CaCO3 content ≥ 90%) and particle size uniformity (40-80mm) of limestone directly affect the calcination efficiency. Impurities such as SiO ₂ and MgO can reduce lime activity and may form low melting point compounds, leading to nodulation; Excessive particle size can lead to incomplete central calcination, while insufficient particle size can increase resistance inside the kiln. The use of pre screening system and stone washing process can effectively improve the quality of raw materials.
3. Improve the combustion system and fuel ratio
Traditional vertical kilns often use a mixed combustion method (mixing fuel and limestone), but the thermal efficiency is relatively low. Modern vertical kilns tend to adopt gas or liquid fuel external combustion designs, such as natural gas, liquefied gas, or low sulfur heavy oil, combined with efficient burners to ensure uniform flame distribution. In addition, optimizing the air-fuel ratio (air to fuel ratio) can reduce incomplete combustion and improve thermal energy utilization efficiency.
4. Strengthen waste heat recovery and exhaust gas treatment
During the lime calcination process, the temperature of the exhaust gas at the kiln top can reach 200-400 ℃, and direct discharge will cause huge energy waste. The use of heat exchangers or waste heat boilers to recover heat can be used to preheat combustion air or dry raw materials, reducing overall energy consumption. Meanwhile, optimizing the dust removal system (such as bag dust removal) can reduce dust emissions and meet environmental requirements.
5. Intelligent control and process monitoring
Introducing DCS (Distributed Control System) or PLC automation system to monitor real-time parameters such as temperature, pressure, CO/O ₂ content inside the kiln, dynamically adjust fuel supply and air flow distribution, can significantly improve calcination stability. By combining infrared thermal imaging or laser particle size analysis technology, the calcination state can be accurately determined, avoiding errors caused by manual experience.
Improving the calcination efficiency of lime vertical kiln is a systematic project that requires collaborative optimization from multiple dimensions such as equipment, raw materials, combustion, heat recovery, and intelligent control. In the future, with the application of new technologies such as oxygen enriched combustion and electric heating calcination, the energy efficiency and environmental performance of vertical kilns will be further improved, promoting the development of the lime industry towards high efficiency and low-carbon direction.
