Overview and Application Fields of Four Channel Burners:
The HTX series four channel coal powder burner is designed specifically for different capacity types, coal powder characteristics, and process conditions using international advanced technology.
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.
At present, it has been widely used in various kiln types such as cement kilns, pellet kilns, lime capacity kilns, lithium kilns, magnesium oxide kilns, alumina kilns, chromate kilns, beneficiation kilns, etc. in industries such as building materials, metallurgy, chemical engineering, and power generation. The four channel burner has advanced technology, precise processing, unique nozzle material, high temperature resistance and wear resistance, long service life, and easy replacement.
2、 Structural characteristics of four channel coal powder burner:
Structure and performance characteristics
The HTX series four channel pulverized coal burner is composed of pipelines, nozzles, metal ripple compensators, butterfly nets, pressure measuring instruments, and protective layers.
Pipeline: including axial flow air duct, swirl air duct, coal air duct, central air duct, and fuel pipe. Because the fuel pipe is used for ignition, it is commonly referred to as a four channel system.
Nozzles: Made of special materials, the nozzle area of each series of burners can be adjusted to adjust the wind speed, which is one of the key components to ensure the shape and lifespan of the flame.
Metal ripple compensator: It is the main component that connects various pipelines, seals, and adjusts the shape of the flame.
Butterfly valve: used to regulate air volume.
Pressure measuring instrument: indirectly displays the spray speed of the air outlet inside the burner.
Protective layer: refers to the fire-resistant casting layer, which is washed by the user.
The four channel 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 just after leaving the nozzle. The internal air adopts stable plate technology to achieve the best stable effect of the flame. At the same time, the temperature of the nozzle is lowered to improve the service life of the nozzle, protect the kiln skin, and extend 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 and 10% anthracite can be used. NOx exhaust emissions can be reduced by more than 30%.
The product structure of the four channel coal powder burner is a type of problem encountered in the engineering practice of the four channel coal powder burner, and the nozzle structure of the four channel coal powder burner has been determined.
From the inside out, it is the central wind, swirling wind, coal wind, and direct current wind in sequence; The channel can also be equipped with an ignition oil gun in the central air channel according to user requirements. The central air flows out through small holes distributed on the central flame stabilizing plate, with a flow rate of about 0.03% -0.05% of the total primary air volume. 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 can not only reduce aerodynamic resistance, And it can generate sufficient swirl strength.
The design of the coal air channel is scientific, and it is not easy to block and adhere ceramics to the parts that are prone to wear and tear during use to ensure its service life. The DC air channel is equipped with 12-16 nozzles distributed in a circumferential direction, and the special cavity linear design and processing accuracy of the nozzles can make the gas flow out of the nozzle rigid and powerful, reduce energy loss, increase the outlet momentum of the DC external air, and improve the injection manifold. In addition, there is a flame stabilizing cover outside the DC air channel to avoid premature flame divergence, At the same time, it also plays a role in protecting the nozzle head.
Both theory and experiment have proven that the center disc flame stabilizer helps to form an internal reflux zone, and 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, the use of 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 four channel pulverized coal 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 a four channel 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, the primary wind should be reduced; The wind speed must be increased once. 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 160-250M/S for direct current external air, 120-245MS for swirling internal air, and 20-35M/S for coal air. Basically meets the aforementioned requirements. The effectiveness of industrial applications has 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 four channel pulverized coal burner has multiple adjustment methods. The different ratios of internal and external air and the outlet jet flow pattern can be adjusted steplessly under the condition of constant total air volume, thus obtaining a flame shape that can adapt to any working condition.
2. Books can reduce coal consumption: Due to the low primary air volume and the optimal 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. Theory and practice have shown that every 1% reduction in primary air; The quantity can reduce heat consumption by 8.70~10.46kJ/kg of fuel. Meanwhile, the secondary air temperature has significantly increased.
3. It has strong adaptability to coal, and can be used for low volatile coal or anthracite. According to the volatile content (%) of combustion, the fineness of pulverized coal should be properly adjusted (generally the 0.080mm sieve residue percentage should be controlled at 0.5~0.75 times of the volatile content). At the same time, the thrust of the burner should be adjusted accordingly, so that low volatile coal or anthracite can be used for rotary kiln burning.
4. Low NOx emissions: During normal operation, there is a negative pressure zone formed by high-temperature smoke backflow 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 production of combustion NOx and high-temperature NOx, with a reduction of 20-30%. The flue gas emissions meet environmental 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 two years at 1100 ° C.
7. Convenient and flexible positioning adjustment:
The suspension device of the four channel powder burner can retract and deflect according to the working conditions inside the nozzle, adjust its working position inside the nozzle, and make the thermal system stable and auxiliary. 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 to produce expansion and extension effects at the nozzle.