In the cement industry, the burner, as a core component of the clinker burning system, plays a crucial role. It is responsible for injecting a mixture of pulverized coal and air into the rotary kiln, igniting and fully combusting it in a high-temperature environment, thus providing the driving force for clinker calcination. The performance of the burner directly affects key indicators of the calcination system, such as clinker output, quality, heat consumption, and pollutant emissions, and is also related to the service life of refractory bricks.

Innovative design of multi-channel burners: Multi-channel burners further improve the efficiency of cement clinker calcination systems. With a multi-channel design, this burner not only achieves uniform mixing of pulverized coal and air, but also achieves more stable combustion in high-temperature environments.

Combustion theory of burners After the fuel is injected into the rotary kiln by the burner, a reasonable flame shape is crucial for meeting the temperature gradient distribution in the kiln. This shape not only affects the reaction temperature of the raw materials in various sections, but also relates to the energy support of the flame. The "relative thrust" representation of the burner is widely adopted.

The length of the pulverized coal burner flame is mainly affected by the mixing rate of fuel and oxygen in the combustion air, which is determined by the unit thrust of the burner, i.e., the momentum of the primary air and the flow rate of air transported per unit time. The thrust affects the flame temperature: a large thrust results in a short flame, and the latent heat of the fuel is released in a smaller space, resulting in high temperature; while reducing the thrust lengthens the flame, and the temperature decreases accordingly. Thrust calculation involves multiple factors, with airflow injection being key. Thrust is calculated by the formula M = A × V, where M is the relative unit thrust of the burner, A is the volume percentage of primary air, and V is the ejection velocity of primary air at the end face. It should be noted that the wind speed of each channel in a multi-channel burner is different, so V is a weighted average. However, thrust is not the only indicator for measuring burner performance. The Danish company, FLSmidth, recommends that the relative thrust should be controlled within the range of 1250～1850%·m/s to achieve optimal use. When the actual coal quality is poor, a larger M value should be taken; when the coal quality is good, a smaller M value should be taken.

Axial primary air volume and injection velocity: Flame Length and stiffness are important indicators for evaluating burner performance. For a specific fuel, the minimum thrust required for complete combustion within a specific time and space is determined. Therefore, for multi-channel burners, the selection range of axial thrust is limited. Within this range, if the amount of primary air is reduced, the axial injection velocity needs to be increased accordingly. Different burner designs will have different momentum ranges and axial injection velocities. Currently, the axial injection velocity of some burners is usually designed in the range of 120～380m/s At the same time, the ejection velocity Vi of each channel is proportional to the air volume Qi and inversely proportional to the cross-sectional area Si of each channel.

When fuel is burned in the kiln, the required air consists of two main parts: firstly, low-temperature primary air injected through the burner, and secondly, high-temperature secondary air from the grate cooler. In the combustion process, if the proportion of primary air is reduced, the proportion of secondary air will increase accordingly. Reducing the amount of primary air in the burner not only helps save energy but also effectively reduces NOx emissions.

Radial swirl intensity: After ensuring the length and stability of the flame, it is necessary to further consider the movement path of the fuel in the rotary kiln, the flow field distribution of gas components, etc. The burner should maintain a suitable gas flow field during operation to ensure efficient fuel combustion. Inside the rotary kiln, the diffusion process of the fuel is crucial to its combustion speed and the formation of the temperature gradient. In order to promote the rapid volatilization and combustion of pulverized coal, increase the temperature at the root of the flame, accelerate the combustion of fixed carbon, and shorten the distance between the flame center and the kiln head, we need to enhance the swirl intensity of the burner.

In the combustion process of the rotary kiln, the flame morphology is crucial to combustion efficiency and the stability of the kiln atmosphere. The "radial diffusion coefficient" is used to characterize the thickness and thinness of the flame, providing a new approach for burner design calculation. By introducing a series of relevant parameters, such as the mass flow rate of air per unit time, the radial component velocity of the jet air, the size radius of the end face channel of the spray combustion tube, the axial component velocity of the jet air, and the net clearance radius of the rotary kiln, the radial diffusion coefficient can more accurately reflect the morphological characteristics of the flame, thus providing strong support for the optimized design of the burner.

Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd.'s "GX" series pulverized coal burners have the following characteristics: Firstly, energy saving is achieved by reducing the amount of primary air at normal temperature and increasing the amount of high-temperature secondary air; secondly, the high wind speed and strong swirl design make the mixing of fuel and air faster, thus enhancing the combustion efficiency of the pulverized coal burner; finally, the flexible adjustment method allows the flame shape to be adjusted in real time according to the kiln conditions to meet different production needs.

Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd. undertakes domestic and international projects: cement kiln head (natural gas, pulverized coal) burners, decomposition furnace burners, cement kiln DCS systems, high-temperature industrial television, and denitrification equipment general contracting projects.