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Operation and requirements for four air duct pulverized coal

Date:2019-04-02 15:25     writer:admin     Views:

  The kiln head burner plays an important role in the calcining of clinker in the kiln. Its performance and whether the adjustment is reasonable will directly affect the calcining in the kiln and the service life of the kiln lining.

  The butterfly valve opening degree of external air, internal air and central air of the burner should be adjusted reasonably to improve the local coal powder concentration in the area before the ignition of pulverized coal, strengthen the internal and external flow of high-temperature gas in the burner, strengthen the full mixing of primary air, and achieve complete combustion.

  However, it must be noted that the internal wind cannot be adjusted too much, or it may cause the coal powder to be diluted before the fire, which is not conducive to the fire, or it may cause the high temperature flame to wash the kiln skin, resulting in the peeling of the kiln skin, which is not conducive to the protection of firebrick.

  The internal wind should not be too small, otherwise the pulverized coal cannot be mixed with air quickly after ignition, which will lead to the reduction of the reaction rate of pulverized coal, resulting in a large amount of carbon monoxide that cannot be oxidized into carbon dioxide in time, resulting in the reduction atmosphere in the kiln.

  In addition, it is not recommended to adjust the external wind too much, or it will cause the burning flame to move backward, and the thick kiln skin at the end of the kiln or the formation of rings and eggs near the transition zone. The external wind should not be too small, or it will not generate strong flame, which is not conducive to calcining good quality clinker.

  Therefore should choose according to the specific situation and reasonable operating parameters, according to the stand or fall of coal quality, fineness, water, secondary air temperature, furnace condition and st. Louis ording to burn sex, by adjusting the best outside wind, endogenous wind and center the proportional relationship of the wind, and the reasonable position of the burner in the kiln mouth nearby, determine the appropriate calcination system.

  1. Positioning of burner

  Many companies use "light column method" burner positioning, control accurate, but not easy to operate.

  It is better to use the position scale to locate on the kiln head section. Generally, it is better to control the position slightly to the right of the X-axis or slightly to the fourth quadrant of the kiln head section.

  Minor adjustments may be made under special process conditions.

  2. Influence of flame shape on calcining

  The optimal flame shape of burner design is the position of axial flow wind and swirling flow wind (at this time, each duct has the maximum ventilation), and the flame shape is complete and powerful.

  Burner lateral distribution.

  Adjusting the shape of the flame is done by adjusting the cross-sectional area of each duct.

  At the position of (0.0), the cross-sectional area of axial and swirling wind reaches the maximum.

  The flame shape is obtained by the mutual influence and mutual restriction of the swirling wind and the axial wind, and the stability of the flame shape is achieved by the central wind, whose air volume cannot be too large or too small.

  Generally, the pressure of the central wind should be controlled between 6-8kpa, which is ideal. When the swirling wind is between 24-26kpa and the axial wind is between 23-25kpa, and the ventilation cross-sectional area of each air duct is not less than 90%, the parameters should be adjusted.

  In order to obtain the change of flame shape, a stable primary air outlet pressure is needed to maintain it. The purpose of changing the flame shape is to stabilize the pressure on the burner and change the ventilation cross-sectional area of each branch pipe.

  Specific flame shape changes.

  When adjusting the shape of the flame, you should avoid going to extremes. When the flame is too thick, it will be very long and soft.

  When the flame is too thin, the flame will be too short, burning zone requires the shape of the flame complete, lively, strong, which requires our long-term observation and summary of experience.

  3. Influence of coal quality change on flame shape

  (1) when the coal ash is high, the burning speed of coal powder becomes slow, the flame becomes longer, the flame burning belt becomes longer, should (1) increase the temperature of secondary air or use more secondary air, strengthen the degree of mixing of primary air and secondary air and coal powder;

  (2) reduce the fineness and water content of coal powder;

  (3) change the proportion of axial and swirling winds;

  (4) increase the primary air volume, reduce the concentration of coal in the primary and secondary air.

  (2) when the coal volatiles become high, the coal powder fires quickly, the oxygen concentration around the coke particles decreases, easy to form near the kiln head, stable low, high temperature part of the flame longer, at this time should increase the oxygen concentration around the flame;

  (2) increase the axial wind volume and wind speed (in the original state of the flame);

  (3) increase the wind volume.

  (3) when the moisture of coal increases, its external moisture can improve the grinding temperature of the gas to reduce, the internal need to around 110 ℃ to evaporation, water coal mill to reduce internal moisture content is difficult.

  High inner water after pulverized coal into the furnace flame will become long, slow burning, the flame temperature is low, the rotor, then should be proper increase of secondary air on the flame combustion, increase secondary air mixed with a wind of air volume, increase secondary air temperature, turn the burner exit some appropriate, use of secondary air to improve the flame burning velocity, achieve the goal of improve flame temperature.

  4. Influence of burner position on kiln condition

  When the burner is installed in the horizontal position, the center point and the cross section center point of the kiln are at the same point. At the end of each overhaul, the position of the burner should be calibrated and checked once more. In normal production, the correct position of the burner and the methods for adjusting the combustion camouflage are as follows:

  (1) in the kiln, the shape of the flame should complete strong, lively, not scour kiln skin, also can't top material calcined, outer flame of fire in contact with the material with stove, if the location of the burner is too partial, the flame will flush into the kiln, kiln cylinder local high temperature, reduce the service life of kiln lining, and the calcining zone of the kiln will be backward outspread, furnace thermal system disorder, serious when, soon red kiln feeding.

  At this time, the burner should be appropriately adjusted to the direction of the material, so that the external flame of the flame and material contact.

  If the position of the burner is too close to the material, the flame will resist the material, resulting in top fire forced burning, incomplete combustion of coal powder is wrapped by the rolling material, burning zone reduction atmosphere is serious, reducing the quality of clinker.

  Gases with serious reducing atmosphere are brought into the preheater system to reduce the temperature of the liquid phase of the material, so that the preheater system can be crustened or even blocked, affecting the normal calcination of the kiln. At this time, the burner should be appropriately adjusted to be far away from the material to make the flame smooth and powerful.

  (2) the scanning image of the central control cylinder is more intuitive and convenient.

  1 the calcining zone of the kiln skin should be between 20 and 25 m, (small kiln kiln skin shorter, big kiln kiln skin longer), connect body to uniform temperature distribution, no high temperature point, the temperature at 300-350 ℃, transition zone with perfect temperature about 350 ℃, the flame complete at this time, lively, smooth.

  The burner is in the right position and the clinker is also in the ideal state.

  (2) the temperature is higher, and the part behind the firing temperature is normal, showing the position of the burner far from material, or the flame has been bifurcate, become loose, fire, processing method: a, open stabbed in kiln hood lateral hole, each class with artificial or conditional use air gun regular cleaning, found that the problem should be handled in a timely manner, otherwise it will affect the production and quality of clinker.

  B. Adjust the shape of the flame and leave a little black flame at the root of the flame to avoid excessive flame temperature.

  My experience is that coking and splitting are hard to avoid, but color management can greatly reduce.

  If the temperature of part of the sintered zone is low, the size of the clinker is different and the granulation is uneven, indicating that the burner is at a low position on the Y-axis.

  (3) after the firing temperature on the high side, especially after 2 belting leather, even above 380 ℃, the burner in the y in high position.

  (4) the temperature of the sintering zone is low, and the temperature of the transition zone is not high, indicating that the kiln skin of the sintering zone is thick, the burner is too close to the material, and the flame is not smooth, so stick it into the material.

  After the clinker is broken, the core is yellow.

  5. Adjustment of normal and abnormal conditions

  In normal operation, if the temperature of the sintering zone in the kiln is low, the opening degree of the internal air butterfly valve should be increased and the opening degree of the external air butterfly valve should be reduced to shorten the flame and increase the pre-kiln temperature.

  When the temperature of sintering zone is high, the opening degree of external air butterfly valve should be large, and the opening degree of internal air butterfly valve should be small, so as to make the flame elongate, maintain a certain speed of the kiln, and improve the output and quality of clinker.

  If found thick kiln stove or ring, should be disposed in time, otherwise it will affect the yield and quality of clinker, into the furnace burner that outside the wind butterfly valve fully open, endogenous wind butterfly valve is short, the center of butterfly valve will open a big wind, make the flame, burning with ward, improve the body temperature, if found burnt with a flat piece of material, certificate after circle has dropped, the burner all back to the furnace mouth position, outside the wind butterfly valve closed small open degree, endogenous wind butterfly valve open big, center of butterfly valve to close small wind, shorten the flame, improve kiln speed, good control of clinker junction temperature, protect the calcining zone kiln.

  Because there are many factors of forming ring, it is not difficult to deal with it as long as the method is reasonable according to the structure of kiln and forming ring.

  6. Several requirements

  (1) before using the new product, be sure to read the manual in detail and operate according to the requirements in the manual.

  (2) determine the best position of burner in the kiln.

  (3) under normal conditions, the burner is calcined at the position of 0-300mm at the kiln mouth.

  (4) the burner moves 1-2 times per shift, back and forth, which is good for protecting the kiln skin and preventing ring formation.

  (5) always observe the pressure gauge display on each air duct and operate according to the parameters on the pressure gauge.

  (6) the clearance (sectional area) adjustment of each air duct is the main adjustment method, no special circumstances, good adjustment, no longer allow any adjustment, can be adjusted according to the butterfly valve on each air duct, butterfly valve is fine tuning.

  (7) the equipment on the pulverized coal burner should be kept intact and problems should be dealt with in time.

  Otherwise, the performance of the flame will be affected.

  (8) when the kiln is stopped each time, the net fan should not stop, but maintain a certain amount of air, not too large, to avoid burning or deformation of the burner head parts.

  (9) select the appropriate batching scheme

  The pulverized coal of the four air channel burners burns fast and the flame temperature is high.

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