What type of lime kiln has the highest production capacity
In the field of lime production, there are various types of lime kilns, among which the rotary kiln has the largest single kiln production capacity. The rotary kiln stands out among many types of lime kilns due to its unique advantages and has become the preferred kiln type for large-scale lime production.
1、 Composition and function of lime kiln
The lime kiln is mainly composed of kiln body, feeding device, material distribution device, combustion device, ash discharge device, electrical appliances, instrument control device, dust removal device and other parts. These components work together to complete the calcination process of lime.
The kiln body is the core part of the lime kiln, providing space and environment for the calcination of lime. The feeding device is responsible for transporting raw materials (usually limestone) into the kiln, while the material distribution device ensures that the raw materials are evenly distributed in the kiln to improve the calcination effect. The combustion device provides the required heat for the calcination process, and the ash discharge device is used to discharge the calcined lime from the kiln. The electrical and instrument control devices achieve precise control and monitoring of the entire operation process of the lime kiln, while the dust removal device plays a role in reducing dust emissions in the exhaust gas and protecting the environment.
2、 Advantages of rotary kiln
High quality lime production
The quality of lime roasted in rotary kilns is the best among all kiln types. It can provide uniform temperature distribution and sufficient calcination time to ensure sufficient reaction of lime, thereby producing high-quality, highly active lime with low carbon dioxide, sulfur, and phosphorus content, meeting the strict requirements of industries such as steel and chemical for high-quality lime.
Strong adaptability of raw materials
The rotary kiln can calcine crushed stone materials with a diameter of over 5mm, which is beneficial for fully utilizing mining resources and reducing the cost of crushing and processing raw materials. Compared to other kiln types that limit the particle size of raw materials, rotary kilns have greater flexibility in selecting raw materials.
High degree of mechanization
Rotary kilns have a high degree of mechanization, with relatively simple control systems and easy production operations. The automated processes of loading, distributing, burning, and unloading not only improve production efficiency, but also reduce manual labor intensity and minimize human interference in the production process, ensuring the stability of product quality.
Large single kiln production capacity
This is one of the most significant advantages of rotary kilns. At present, the single kiln production capacity of rotary kilns can reach 200 tons/day to 1200 tons/day or even higher, which can meet the demand for large-scale lime production. Large scale production is beneficial for enterprises to achieve economies of scale and reduce the production cost per unit of product.
Wide adaptability of fuel
Rotary kilns can use coal powder, various combustible gases, etc. as fuel, which enables enterprises to choose the most economical and reasonable fuel based on their own energy supply situation and cost considerations, thereby further reducing production costs.
Good cleanliness of finished ash
The calcination process of rotary kiln is relatively closed, which can effectively reduce the mixing of impurities, almost without impurities, and ensure the cleanliness of the finished ash.
3、 Comparison with other types of lime kilns
In order to gain a clearer understanding of the characteristics of rotary kilns, we compared them with other common types of lime kilns.
Double chamber vertical kiln
Double chamber vertical kiln is a type of imported vertical kiln, which has the advantages of good quality of calcined lime, full utilization of waste heat energy, high thermal efficiency, small footprint, low exhaust gas temperature and dust content, easy to adopt exhaust gas purification measures, and conducive to reducing environmental pollution. However, the mechanical equipment of the double chamber kiln is complex, requiring high quality operators, positive pressure operation of the kiln body, difficult maintenance, and strict requirements for coal quality when using coal powder as fuel. In addition, its single kiln production is relatively low compared to rotary kilns.
Sleeve vertical kiln
Sleeve vertical kiln also belongs to the imported type of vertical kiln, and its advantages are similar to double chamber vertical kiln, such as better lime quality, higher thermal efficiency, and smaller footprint. But its kiln structure is complex, requiring high quality refractory materials and masonry for kiln lining, and requiring a large amount of daily maintenance work.
Domestic gas fired vertical kiln
Domestic gas fired vertical kiln is a traditional kiln type developed domestically, which has the advantage of moderate lime quality and the lowest construction investment among active lime kilns; Due to the use of coal gas as fuel, the quality of lime can reach the lower limit of the active lime standard when the raw fuel meets the requirements. But the shortcomings of this kiln type are also quite obvious, such as high exhaust gas temperature at the kiln roof, low thermal efficiency, and low single kiln output.
Coke vertical kiln
The traditional mechanized coke vertical kiln is one of the main thermal equipment for roasting metallurgical lime in China. Its advantages are low investment, simple structure, and easy operation. However, this type of kiln has problems such as uneven fabric distribution and lack of effective control measures, resulting in unstable product quality, large fluctuations in indicators, and severe overheating.
Through comparison, it can be seen that although rotary kilns have relatively high heat consumption, equipment weight, footprint, and investment, their advantages in lime quality, single kiln production capacity, and raw material adaptability make them irreplaceable in large-scale lime production.
4、 The Development and Application of Rotary Kilns
With the continuous advancement of technology and the growth of market demand, rotary kilns are also constantly developing and improving. For example, by optimizing the kiln structure design, improving the combustion system, and enhancing the efficiency of waste heat utilization, energy consumption has been further reduced, production efficiency and product quality have been improved.
In practical applications, rotary kilns are widely used in industries such as steel, chemical, and building materials. For example, in steel enterprises, high-quality lime is an indispensable raw material in the steelmaking process, and rotary kilns can stably provide lime that meets the requirements, playing an important role in improving the quality of steel.
The 4 × 1000 ton active lime roasting rotary kiln project of Shandong Rizhao Huasheng Resources, which was once contracted by CITIC Heavy Industry, is a typical case of the application of rotary kilns in large-scale lime production. The project includes four production lines with a daily output of 1000 tons of active lime roasting rotary kiln, with a production scale of 1.2 million tons. Currently, the actual production capacity has reached 1100 tons per day, exceeding the planned output value. CITIC Heavy Industry has adopted the industry's first blast furnace gas preheating and kiln tail combustion technology in this project, which has unparalleled advantages in achieving high yield, low consumption, and energy conservation. It has important demonstration significance for improving the technical level and energy conservation and emission reduction of the entire industry.
5、 Future Development Trends
Against the backdrop of increasingly strict environmental requirements and improving resource utilization efficiency, the future development trends of rotary kilns mainly include the following aspects: Further improve energy utilization efficiency, reduce energy consumption, and minimize production costs and environmental impact. Optimize the temperature distribution and atmosphere control inside the kiln to improve the stability and consistency of lime quality. Strengthen the purification treatment of exhaust gas, reduce pollutant emissions, and meet stricter environmental standards. Combined with intelligent technology, achieve automated control and remote monitoring of the production process, improve production efficiency and management level. As the lime kiln with the largest single kiln production capacity, the rotary kiln occupies an important position in the lime production industry due to its advantages of high-quality lime output, strong adaptability to raw materials, high degree of mechanization, large production capacity, and wide fuel adaptability. With the continuous advancement and development of technology, rotary kilns will continue to leverage their advantages to provide high-quality lime products for various industries, and make continuous contributions in energy conservation, emission reduction, and improving resource utilization efficiency. In the future lime production, rotary kilns will still be the preferred kiln type for large-scale and high-quality lime production, leading the development direction of lime kiln technology.
