Principle of pulverized coal burner:

The pulverized coal is carried by the air flow and sprayed out from the coal duct at a certain diffusion angle. The combustion-supporting wind on the outer side imparts a relatively high momentum and moment of momentum. The swirling air on the inner side is mixed with the jetted pulverized coal airflow at a high speed It advances in a spiral and meets the high-speed axial wind beam. The insertion of the axial wind beam further enhances the mixing of coal and wind (including the surrounding secondary air), and can adjust the degree of flame divergence, and the length and thickness of the flame can be adjusted as needed to achieve the required flame shape. The role of the central wind is to promote the combustion of a small amount of coal and CO in the central part, so that the combustion is more complete, and it acts as a steady flow. Due to this combustion mechanism and the high speed of the cyclone and axial flow, the combustion is very rapid and complete.

Features:

(1) The structure design is reasonable and the flame adjustment is convenient. In addition to adjusting the air volume of the suction air and the swirling air, the cross-sectional area of the swirling air outlet can also be adjusted to achieve the purpose of changing the outlet wind speed of the burner and ensure the normal combustion of fuel.

(2) Each air pipe of the burner is connected by a flange, which is easy to disassemble and easy to maintain.

(3) The nozzle material is unique, high temperature resistant and easy to replace.

(4) Reduce the content of CO and NOX: Because the combustion-supporting air and pulverized coal are more fully mixed, the combustion is faster and complete, and the content of CO and NOX in the exhaust gas of the kiln tail is reduced, which is conducive to the safe operation of electric dust collection and environmental protection.

Brief introduction of multi-channel pulverized coal burner structure:

The innovative multi-channel gas-gas mixed combustion burner of Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd. is divided into: adjustable and non-adjustable channel outlet cross-sectional area. It is composed of pipelines, nozzles, pressure measuring instruments and protective layers.

Pipeline: There are five lines from outside to inside, which are axial flow duct, cyclone duct, blast furnace gas duct, coke oven gas duct and central duct.

Nozzle: Processed by special materials, it is one of the key components to ensure the flame shape and life.

Butterfly valve: used to adjust the air volume. Three manual butterfly valves are installed on the burner of the rotary kiln, which are used to adjust the flow of central air, cyclonic air and axial air respectively.

Pressure measuring instrument: Indirectly display the spraying speed of each tuyere in the burner and the pressure of gas.

Protective layer: the refractory cast layer, the user is responsible for pouring

The four-channel pulverized coal burner uses the principle of large speed difference in the same direction co-flow, and makes full and effective use of the secondary air, so that the temperature of the pulverized coal will quickly increase to the ignition point, and a thick cone-shaped flame will be formed just after leaving the nozzle. The technology enables the flame to achieve the best stabilization effect, while reducing the nozzle temperature and increasing the nozzle service life. Protect the kiln skin. Extend the service life of the kiln lining. The primary air consumption only accounts for 5-7% of the theoretical air consumption, which is significant in energy saving. Anthracite with a content of 30-35% lignite and a volatile content of about 10% can be used. N0x exhaust emissions can be reduced by more than 30%. Specifications and performance parameters

The product structure of the four-channel pulverized coal burner is a variety of problems encountered by Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd. in the engineering practice of the three-channel pulverized coal burner. The nozzle structure of the four-channel pulverized coal burner is determined. From the inside to the outside, It is followed by central wind, cyclone wind, coal wind, direct-flow wind channel, and an ignition oil gun can be installed in the central wind channel according to user requirements. The central wind flows out through the small holes distributed on the central flame stabilizing plate, and the flow is about the primary wind 0.03%-0.05% of the total, its function is to adjust the negative pressure of the return zone in the center of the jet, and change the position and size of the high temperature zone of the head. The swirling wind channel adopts a long spiral blade shaft cyclone, and its unique structure can not only Reduce the aerodynamic resistance, and can produce enough swirl intensity.

The coal-air channel is designed scientifically, it is not easy to be blocked in use, and the ceramic is adhered to the vulnerable parts to ensure the service life. The direct-flow air channel is installed with 12-16 circumferentially distributed nozzles. The nozzle's special cavity linear design and processing accuracy can be Make the nozzleoutflow stiff and powerful, with less energy loss, increase the outlet momentum of the DC external wind, and improve the jet manifold. In addition, there is a flame stabilizing cover outside the DC air channel to avoid premature flame divergence and protect the nozzle at the same time The role of the head.

Theories and experiments have proved that the central disc flame stabilizer helps to form an internal recirculation zone, and the geometry of the swirling air outlet will play an important role in the velocity of the jet and the position of the internal recirculation zone. Under the same swirling intensity conditions , The use of the expansion port can increase the radial distance between the axial and tangential velocity peaks and the reverse mass flow. The inner and outer pipes of the swirling air passage of the four-channel pulverized coal burner adopt an axial expansion and contraction structure, which can be adjusted in real time according to the working conditions, so that the nozzle has an expansion and extension effect. Operational practice has proved that this kind of adjustment method is extremely effective in controlling the flame shape.

The product of the primary air mass flow m (kg/s) of the four-channel pulverized coal burner and its ejection velocity is called the thrust M (N) of the burner. During the combustion process, the mixing rate of the secondary hot air and pulverized coal and the combustion speed of pulverized coal increase with the increase of the thrust of the burner, but excessive thrust will also have negative effects. It can be seen from the above that if the value range of thrust or relative momentum is limited, the primary wind speed must be increased to reduce the primary air volume. It can be roughly estimated that the primary wind speed corresponding to the primary air volume is about 180-220M/S. At present, the speed of most domestic three-channel burners does not reach this value.

The range of primary wind speed for the four-channel pulverized coal burner is 160-250M/S for direct current outside wind, 120-245M/S for swirling inside wind, and 20-35M/S for coal wind. Basically meet the aforementioned requirements. The effect of industrial application also confirms that increasing the momentum of the primary air outlet can effectively reduce the primary air volume.

Features:

1. Good flame shape adjustment: The four-channel pulverized coal burner has a variety of adjustment methods. The different ratios of internal and external air and the outlet jet flow pattern can be adjusted steplessly in a wide range under the condition of the total air cooling unchanged, so as to obtain energy Adapt to any flame shape under any working conditions.

2. Energy saving and consumption reduction: Because the primary air volume is low, and the direct current and cyclone air can be adjusted to the best ratio, it is conducive to the complete combustion of pulverized coal. Therefore, the four-channel pulverized coal burner can effectively reduce coal consumption. The theory and practice show that every reduction of 1 % Of the primary air volume can reduce the heat consumption by 8.70～10.46kJ/kg fuel. At the same time, the secondary air temperature is significantly increased.

3. It has strong adaptability to coal and can be used for low volatile coal or anthracite; according to the combustion volatile content (%), adjust the fineness of coal powder (generally, the percentage of 0.080mm sieve is controlled at 0.5 to 0.75 times the percentage of volatile ), while adjusting the thrust of the burner accordingly, the low volatile coal or anthracite can be used for calcination in the rotary kiln.

4. Low NOx emissions: During normal operation, there is a negative pressure zone at the head of the four-channel pulverized coal burner, which is formed by high-temperature flue gas return, which can avoid local high temperature and change smoothly along the temperature curve of the kiln length, thus effectively inhibiting "combustion" The production of "NOx" and "high temperature NOx" has been reduced by 20-30%, and the flue gas emissions have reached the national environmental protection emission standards.

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

6. New technology and new materials ensure the service life: the wear-resistant parts of the four-channel pulverized coal burner have been equipped with special wear-resistant spraying technology, which increases the wear-resistant life of the key parts of the burner by 5-10 times compared with ordinary steel. The head and nozzle of the four-channel pulverized coal burner are made of heat-resistant steel, which can ensure that the burner has a life of more than two years at 1100°C.

7. Convenient and flexible positioning adjustment:

The suspension device of the four-channel pulverized coal burner can be telescopic and deflected according to the working conditions in the kiln, and adjust its working part in the kiln, so that the thermal system is stable and reliable. The inner and outer tubes of the swirling air channel adopt an axial telescopic structure, It can be adjusted in real time according to the working conditions, so that the spout has an expansion and extension effect.

Overview and application fields of pulverized coal burners:

The pulverized coal burner is specially designed by Zhengzhou Zhongwei Environmental Protection Equipment Co., Ltd. with international advanced technology for different kiln types, different pulverized coal characteristics and different process conditions. Its unique structure and reasonable process parameters ensure the full mixing of pulverized coal with primary air and secondary air, high combustion efficiency, high thermal strength, and good flame shape. It has been repeatedly verified in practice and is easy to use and adjust.

At present, it has been widely used in cement rotary kilns, pellet rotary kilns, lime rotary kilns, ceramsite sand rotary kilns, zinc oxide rotary kilns, bauxite rotary kilns and other kiln types in building materials, metallurgy, chemical, electric power and other industries.