Expert of Systematic Overall Solution for Calcium Material Resource Utilization
The principle of the double-beam lime kiln process.
Dec 16,2024
The double-beam lime kiln is a commonly used lime production equipment, with a calcination mechanism of full reverse flow calcination. The core part of the kiln uses a two-layer burner beam, which has multiple fuel pipes inside to supply fuel to the burners. The burners are distributed on both sides of the beam, allowing for uniform distribution of fuel across the cross-section of the kiln, thus ensuring uniform combustion across the entire vertical kiln cross-section.
To reduce the thermal consumption of the kiln, the combustion beam is cooled with heat transfer oil. The heat transfer oil carries heat away through the combustion beam and is used to preheat the primary air required for combustion. This method can effectively improve the fuel utilization rate and reduce energy consumption.
The double-beam kiln has some obvious advantages. First, the brick shape and masonry of its refractory materials are very simple, and compared to other vertical kiln forms, the required weight of refractory materials is lighter. This not only reduces costs but also facilitates construction.
The double-beam kiln also employs a bidirectional pressure system (the latest development is a three-way pressure system). In this system, the area below the calcination zone is under positive pressure, while the area above the calcination zone is under negative pressure. To meet the secondary air required for combustion, the blower injects secondary air into the cooling zone, thus maintaining a positive pressure state below the calcination zone. At the same time, the induced draft fan extracts the exhaust gas from the upper part of the kiln, keeping the area above the calcination zone under negative pressure. This bidirectional pressure system effectively improves combustion efficiency.
In the latest three-way pressure system, a new extraction beam has been added, located 2000mm below the lower burner beam. Behind the extraction beam, a high-temperature fan extracts hot air (hot air generated after cooling the lime) at about 500℃ and sends it to the burner beam, forming a third zero-pressure route. In this area, there is basically no airflow. The introduction of this three-way pressure system further optimizes the distribution of airflow within the kiln and improves heat transfer efficiency.
The double-beam kiln typically uses fluid fuels such as gas, oil, and coal powder. These fuels have high combustion efficiency and are easy to adjust, meeting the temperature and fuel supply requirements of different lime production processes.
However, compared to other vertical kiln forms, the calcination principle of the double-beam kiln is relatively backward, and the lime activity is not high. The lime activity of several domestic double-beam kilns that have been put into production is generally low, even comparable to that of ordinary gas-fired vertical kilns. This limits the promotion and application range of the double-beam kiln.
The double-beam lime kiln is designed with a full reverse flow calcination mechanism, with the core part being two layers of burner beams, achieving uniform combustion across the entire vertical kiln cross-section through the uniform distribution of fuel. Its advantages include simple masonry of refractory materials, lightweight refractory materials, and the application of a bidirectional pressure system. However, compared to other vertical kiln forms, the lime activity of the double-beam kiln is lower, which limits its promotion and application. Future research and optimization work can further improve the lime activity of the double-beam kiln, enhancing its competitiveness and sustainability.
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