1、 Overview and application fields of multi-channel coal powder burners:

The ZWR series four channel coal powder burner is specially designed by Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd. using international advanced technology for different kiln types, coal powder characteristics, and process conditions. Its unique structure and reasonable process parameters ensure the full mixing of coal powder with primary and secondary air, with high combustion efficiency, high thermal intensity, and good flame shape. It has been repeatedly verified in practice and is easy to use and adjust. The multi-channel burner has advanced technology, precise processing, unique nozzle material, high temperature resistance and wear resistance, long service life, and easy replacement.

2、 Structural performance characteristics of multi-channel coal powder burner:

The coal powder burner utilizes the principle of co flow and large velocity difference in the same direction, fully and effectively utilizing secondary air to quickly raise the temperature of the coal powder to the ignition point, forming a thick conical flame as soon as it leaves the nozzle. The internal air adopts stable plate technology to achieve stable flame effect, while reducing the nozzle temperature and improving the nozzle service life. It protects the kiln skin and extends the service life of the kiln lining. The primary air consumption only accounts for 5-7% of the theoretical air consumption, which significantly saves energy, Both 30-35% lignite with ash content and anthracite with volatile content of about 10% can be used, and N0x waste gas emission can be reduced by more than 30%.

The nozzle structure of a four channel coal powder burner is from the inside out: it is sequentially divided into central air, swirl air, coal air, and direct air channels. An ignition oil gun can also be installed in the central air channel according to user requirements.

Central air: It flows out through small holes distributed on the central flame stabilizing plate, with a flow rate of approximately 0.03% -0.05% of the total amount of primary air. Its function is to adjust the negative pressure in the center reflux zone of the jet, change the position and size of the high-temperature zone at the head. The swirl air channel adopts a long spiral blade axial cyclone, which has a unique structure that not only reduces aerodynamic resistance but also generates sufficient swirl strength.

Coal air channel: It is not easy to block during use and adheres ceramics to the parts that are prone to wear and tear to ensure service life. The DC air channel port is equipped with 12-16 nozzles distributed in a circumferential direction. The special cavity linear design and processing accuracy of the nozzle can make the outlet airflow of the nozzle strong and powerful, reduce energy loss, increase the outlet momentum of the DC external air, and improve the injection manifold. In addition, the DC air channel is also equipped with a flame stabilizing cover outside to avoid premature flame divergence, At the same time, it also plays a role in protecting the nozzle head.

After years of practical experience in the rotary kiln burner engineering of Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd., it has been proven that the center disc flame stabilizer helps to form an internal reflux zone. The geometric shape of the swirl air outlet plays an important role in the various velocities and positions of the internal reflux zone in the jet. Under the same swirl intensity conditions, using an expansion type extension port can increase the radial distance between the axial and tangential velocity peaks and the reverse mass flow rate.

The inner and outer sleeves of the swirl air channel of the coal powder burner adopt an axial expansion structure, which can be adjusted in real-time according to the working conditions to produce an expansion and extension effect at the nozzle. Operation practice has proven that this adjustment method is extremely effective in controlling the shape of the flame. The product of the primary air mass flow rate m (kg/s) of the pulverized coal burner and its injection speed is called the thrust M (N) of the burner. The mixing rate of secondary hot air and coal powder during the combustion process, as well as the combustion rate of coal powder, increase with the increase of burner thrust, but excessive thrust can also have negative effects. From the above, it can be seen that if the range of thrust or relative momentum values is limited, to reduce the primary air volume, it is necessary to increase the primary air speed. It can be roughly estimated that the primary wind speed corresponding to the primary air volume is around 180-220M/S. At present, the speed of most three channel burners in China has not reached this value.

The primary wind speed range of the four channel pulverized coal burner is: direct current external air 160-250M/S, swirling internal air 120-245M/S, and coal air 20-35M/S. Practical results have also confirmed that increasing the momentum of the primary air outlet can effectively reduce the primary air volume

1. Good adjustability of flame shape: The coal powder burner has multiple adjustment methods, and the different ratios of internal and external air and the outlet jet flow pattern can be adjusted in a large range and stepless manner under the condition of constant total air volume, thus obtaining a flame shape that can adapt to any working condition

2. Energy saving and consumption reduction: Due to the low primary air volume and the adjustable ratio of direct and swirling air, which is conducive to the complete combustion of coal powder, the four channel coal powder burner can effectively reduce coal consumption. The practice of Zhongwei Environmental Protection Engineering shows that every 1% reduction in primary air volume can reduce heat consumption by 8.70~10.46kJ/kg of fuel. Meanwhile, the secondary air temperature has significantly increased.

3. Strong adaptability to coal, which can be used for low volatile coal or anthracite; According to the volatile content (%) of combustion, properly adjust the fineness of pulverized coal (generally the 0.080mm sieve residue percentage is controlled at 0.5~0.75 times of the volatile content), and adjust the thrust of the burner accordingly, so that low volatile coal or anthracite can be used for rotary kiln calcination.

4. Low NOx emissions: During normal operation, there is a negative pressure zone formed by high-temperature flue gas reflux at the head of the four channel coal powder burner, which can avoid local high temperatures. The temperature curve along the kiln length changes smoothly, thus effectively suppressing the generation of "combustion NOx" and "high-temperature NOx", with a reduction of 20-30%. The flue gas emissions meet the national environmental protection emission standards.

5. Reasonable structure and excellent overall performance: The four channel coal powder burner has a beautiful appearance, complete supporting facilities, low system resistance, convenient and fast flame adjustment, convenient maintenance, and overall performance meets the level of foreign multi-channel burners.

6. New technology and materials ensure service life: Special wear-resistant spraying technology has been applied to the easily worn parts of the four channel coal powder burner, which increases the wear-resistant life of key parts of the burner by 5-10 times compared to ordinary steel. The head and nozzle of the four channel coal powder burner are made of heat-resistant steel material, which can ensure that the burner has a lifespan of more than three years at 1100 ℃.

7. Convenient and flexible positioning and adjustment: The suspension device of the four channel coal powder burner can expand and deflect according to the working conditions inside the kiln, adjust its working position inside the kiln, and ensure stable and reliable thermal system. The inner and outer sleeves of the swirling air channel adopt an axial expansion structure, which can be adjusted in real-time according to the working conditions, making the nozzle expand and extend.

Pulverized coal burners have been widely used in various kiln types such as cement kilns, pellet kilns, lime kilns, lithium kilns, magnesium oxide kilns, alumina kilns, chrome salt kilns, beneficiation kilns, ceramic sand, bauxite, kaolin, etc. in industries such as building materials, metallurgy, chemical engineering, and power. For more details, please feel free to call (WeChat synchronization): 15713691937.