Operation method of rotary
kiln kiln site workers to see fire requirements
1 Look at the "black shadow". It is required to see the "black shadow" and stabilize the "black shadow" position, maintain a certain firing temperature, and control the uniform material to achieve the purpose of high fast-speed.
2 . Look at the lifting height and rolling condition of the clinker to determine whether the temperature of the firing zone is appropriate. When the firing temperature is normal, the material is tumbling flexibly with the kiln, and the lifting height is also appropriate; when the temperature is too high, the clinker is raised high and rolls down in a piece.
3 . Look at the clinker particle size and require the clinker particles to be fine and uniform. When the size of the clinker becomes coarse and the flame is white, it means that the temperature in the kiln is rising, and coal should be reduced as appropriate.
4 . Look at the color of the flame. The normal flame color is slightly white. At this time, the clinker particles are fine and uniform and have a certain vertical weight. When the flame is whitish, it means that the firing temperature is too high and the coal should be reduced. The red color of the fire indicates that the temperature is low and coal should be added. The fire resistance of the materials is different, and the fire color of the control should be different. That is, when the material is more refractory, the fire color should be controlled to be white, otherwise it is the opposite.
5 . It seems that the amount of material is expected to be able to accurately control the change of incoming materials, so as to facilitate the timely and accurate addition and subtraction of pulverized coal to control the temperature of the firing zone. When the raw material enters the firing zone, if the flame is shortened, it means that the material is less increased, and coal should be added appropriately. If the fire color in the back is red, and there is not much material in the firing zone, the coal should be gradually added; if the coal is added, the back will be whitish quickly, indicating that the temperature will increase, then the coal should be reduced in time. When the rear section is bright, the flame is stretched, the "black shadow" is far away or there is no coal added, the fire color turns bright, and the material rolls up fast, indicating that the incoming material is reduced, and the coal should be reduced in time.
6 . Look at the wind coal. In normal operation, if the wind coal is properly matched, the flame remains stable, the shape is complete, the distribution is uniform, and it is lively and powerful. When the coal has less wind, the flame is slender and weak; if the coal is less windy, the flame is chaotic and not concentrated. If the primary and secondary air temperatures are high, the flame is short; when the primary and secondary air temperatures are low, the flame is long. When the coal wind pipe is outside, the flame is short; when the coal wind pipe is inside, the flame is long. The wind coal should be properly matched according to the specific conditions to ensure that the pulverized coal is completely burned and the flame shape is good.
7 . Look at the smoke color. Judging from the color of the chimney exhaust gas, it is judged whether the combustion in the kiln is good or not. If the smoke color is white, it means that the combustion in the kiln is complete; if it is black smoke or black smoke, it means that the coal powder is not completely burned. At this time, the coal should be reduced in time or the small slow train should be properly used. When the smoke is thick and yellow, it indicates the possibility of a ring in the kiln.
8 . Looking at the exhaust gas temperature, it is required to stabilize the exhaust gas temperature as much as possible so that the fluctuation range is as small as possible. If the temperature of the exhaust gas rises or falls, the wind coal should be adjusted in time, and attention should be paid to whether there is a ring in the kiln.
9 . Looking at the kiln skin, it is required to control the kiln skin to be smooth and moderate in operation to ensure the safe operation of the kiln. However, if the kiln skin is found to have deep pits, denudation, partial shedding or hot water, it should be immediately tempered by adjusting the raw material composition, the amount of material to be discharged, the speed of the kiln, the cooling water or the position of the coal powder nozzle.
10 . Looking at the feeding amount, it is required to strictly control the kiln speed and the feeding amount to ensure the uniformity of the raw material into the kiln and the stability of the thermal system in the kiln.
Operation experience of the kiln decomposition kiln system
1.the inspectionbefore the kiln is
Aftersystemcompleted, it is necessary to carry out a detailed inspection of the system, clean all the debris inside the system, and confirm whether the lining material such as refractory brick is firm. Before starting the machine, all the ash discharge valves should be inspected to confirm whether they are flexible or damaged. Check whether the weight of the ash discharge valves at all levels is reasonable to prevent too light or too heavy, resulting in poor mechanical rotation or poor sealing, resulting in air leakage and blockage. In normal production, the ash valve vibrates slightly, which means that the counterweight is reasonable. When opening the kiln, check all the inspection doors, flanges, measuring holes, ash discharge valve shafts, etc. in time to prevent blockage caused by external air leakage. If problems are found to be dealt with in a timely manner, you cannot wait until the next time. Improve process facilities, comprehensive management, and eliminate hidden dangers. Before the feeding, all the ash discharge valves should be moved, and the blowing device should be opened to prevent the cone volume material.
Second, strengthen the operation of
normal production, should be strictly operated, maintain a reasonable distribution of temperature and pressure, both before and after, close coordination; operators must have a good sense of responsibility and predictability. Adding and reducing materials in time, the coal and coal materials are reasonable, and the feed kiln speed is synchronized; diligent inspection, diligent contact, diligent observation, and diligent activities.
Third, the kiln system ventilation control and regulation
In the case of the kiln fuel amount and feed amount is reasonable, the provision of appropriate combustion air to the fuel is the control principle of system ventilation. Generally, the system is controlled based on the analysis of the exhaust gas at the kiln tail, the decomposition furnace and the preheater outlet. The oxygen content of the three parts should generally be controlled by 2%, 2 to 3%, and 3 to 4%, respectively. At the same time, CO should be avoided as much as possible. The control method mainly adjusts the opening degree of the tertiary air valve, and adjusts the air volume of the primary air, the exhaust volume of the kiln head fan, and the bypass air volume to adjust the ventilation of the system.
Fourth, reasonable control of the amount of feed
can be fed, should be timely feeding; the beginning of the kiln feeding should gradually increase the amount of feed, but should try to avoid prolonged low feed stage. It is necessary to have a good grasp of the relationship between fuel, feed and air volume to achieve a reasonable thermal balance. When the feeding is small, the material is easily overheated and the preheater is prone to blockage. When the feed is too large, the material can not be suspended normally, and the preheating is ensured, and the decomposition of the material is not good. When the wind is low at various speeds, the materials are easily piled up in some small platforms inside the preheater and the decomposition furnace, and the cones with small angles. When the wind speed of the system changes, the accumulated material will lose stability and collapse. The stocks quickly broke into the firing zone, seriously interfering with the thermal system.
5. The amount of coal before and after reasonable distribution
1 . The temperature of the kiln tail and the decomposition furnace gas should not be higher than the normal value.
2 . In the case of reasonable ventilation, the oxygen content in the exhaust gas at the exit of the kiln and the decomposition furnace should be kept within an appropriate range, and the excessive CO content should be avoided.
3 . The proportion of the fuel for the decomposition furnace is increased as much as possible under the condition of temperature and ventilation.
The temperature from the kiln tail to the decomposition furnace is high and the skin is severe. The seriousness of the crust is always considered to be caused by the high temperature in the decomposing furnace and the fuel in the decomposing furnace. Therefore, the fuel of the decomposing furnace is always reduced in operation, and then the fuel for the kiln is increased. As a result, the temperature in the region is further increased and the crust is more serious. The kiln condition has further deteriorated, which is actually caused by the kiln fuel. The decomposition furnace is a high-efficiency heat exchanger. In the decomposition furnace, the temperature of the fuel gas is not too high, and the material in the furnace can obtain a high decomposition rate. If the decomposition rate is low to increase the burden on the kiln, the heat exchange efficiency of the kiln is low. In order to ensure the normal calcination of clinker, it is necessary to refuel in the kiln. However, due to the limitation of the heat exchange rate of the fuel, the temperature in the area from the kiln to the decomposition furnace is inevitably too high, and the material is easy to circulate in some corners of the area. , easy to cause serious skinning. Before the material is completely decomposed, its temperature will not exceed the equilibrium at that time (generally around 850 °C). Therefore, proper refueling in the decomposition furnace will not cause the exhaust gas and material temperature in the above area to be too high. However, the temperature of the gas in the furnace and the outlet gas is high only when the materials in the furnace are not well dispersed and the distribution is uneven. Therefore, when the temperature of the kiln tail and the rising pipeline is high, it cannot be easily considered that the fuel in the decomposition furnace is increased, but the reason should be carefully analyzed. Usually, as long as some of the kiln fuel is gradually reduced and a part of the reduction is added to the decomposition furnace, the situation will gradually improve.
The firing temperature is low, and the clinker is not burnt. It is considered to be caused by less fuel in the kiln. Even when the burning capacity of the kiln has reached the limit, the fuel quantity is increased. As a result, the temperature of the kiln head is further lowered, and the temperature of the kiln tail system is high. Will cause the kiln to reduce the atmosphere, resulting in serious system crust, long thick kiln skin, and even ring. There is a simple principle for the increase of kiln fuel. As long as the CO in the kiln exhaust gas exists, the fuel for the kiln head should not be increased before the system state is adjusted to make CO disappear. The reason should be analyzed. If the combustion air is insufficient, try to Increase the ventilation, such as the fan to the limit, then analyze whether the material is too much, whether the tertiary air valve is not adjusted well, whether the kiln is looped, and appropriate treatment and adjustment. If the decomposition rate is low, the cooling efficiency is low, and the secondary air temperature is low, the above phenomenon will occur.
Factors affecting the length of the flame:
1. Fineness of coal powder: The finer the fineness of coal powder, the faster the burning speed, the finer the surface area of coal powder, the larger the surface area of coal and the oxygen in the air, so the burning speed is increased. The length is shortened.
2. Secondary air temperature: the temperature is increased, the burning speed is fast, and the flame is short.
3. The form of the coal nozzle: The form of the coal nozzle affects the mixing of wind and coal. The more uniform the wind coal mixes, the faster the burning speed.
Effect of volatile matter of coal on flame length: bituminous coal with high volatile content can ignite near the nozzle, and the flame is longer, and the coal with low volatile content is opposite (because the ignition temperature decreases with the increase of volatile matter) Therefore, the volatile content is different, the ignition point is different from the nozzle, the volatile content is high and the fire is early, and the heating process of the coal continues for a long distance, so the flame is long. The coal with low volatile content, most of the heat energy is It can be released within a short distance, so that the flame concentrated flame is short, and sometimes local high temperature occurs.
4. The influence of the gas flow rate in the kiln on the flame length The
faster the flow rate, the longer the flame, and the gas flow rate is affected. The effect of primary wind speed and kiln exhaust. One wind speed increases, on the one hand, it can increase the effective range of pulverized coal, and the flame will be elongated; on the other hand, the wind coal will be evenly mixed, so that the burning speed is fast and the flame is short. The opposite effect. At the same time, in order to prevent "tempering", the ejection speed should be greater than the flame diffusion speed. The ejection speed is related to the diameter of the kiln, and the large diameter kiln requires higher The discharge speed, the smaller kiln diameter spray speed takes a small value, which can create good conditions for the heat exchange between the flame and the material. The kiln exhaust increases the kiln tail negative pressure, the secondary air increases, and the flame is outside. The gas flow rate is increased to extend the flame. In normal production, the flame length is changed by changing the kiln exhaust or reducing the third wind to increase the kiln tail pressure.
Factors affecting the shape of the rotary kiln flame:
1. Coal powder The influence of quality and dosage on
the volatile matter of coal powder: low-volatility (≤ 15%) coal powder, easy to form a flame with long black head, short high temperature part and high local flame temperature. High volatile content (> 30%) Although pulverized coal is hot, it takes a certain time for fractional distillation and combustion of volatiles, and the surface gas layer of coke particles is thick. Therefore, when the coke starts to burn, there is not much oxygen around it, so it is close to the kiln head and the temperature is slightly lower. A flame with a long temperature at a high temperature.
The ash content of the pulverized coal: when the ash content of the pulverized coal increases, the calorific value decreases, the burning speed slows down, the flame is elongated and the temperature is lowered.
The moisture of the pulverized coal: when the moisture increases, the flame Temperature drop ,blackelongated
The amount ofcoalattempting:a greater concentration of air in the coal, coal and a longer time for mixing of the secondary air, the combustion duration is long and therefore, when the primary air unchanged. When the amount of coal is increased, the flame will elongate.
2. The position and shape of the
coal injection nozzle. The position of the coal injection nozzle: When the position of the coal injection nozzle is inside the secondary air into the kiln position, the first and second winds are weakly mixed and extended. Burning time, the flame is extended. If the secondary air enters the kiln position, the mixing between the primary and secondary winds will be strengthened to shorten the flame. The
shape of the coal injection nozzle: the speed of the coal outlet of the straight nozzle is small. Therefore, the pulverized coal has a close range and a thick flame. The outlet coal of the pull-out nozzle has a large exit velocity, the pulverized coal has a long range, and the flame is concentrated. The flame sprayed after the coal-fired tube is loaded with the wind fin is shorter than when the wind-winged wing is not installed. Concentration.
3, the influence of the primary wind
: for the high volatile coal, should use more than one wind, otherwise, the volatiles can not burn quickly, the flame will be elongated, the temperature should also be reduced. For coal with low volatiles, should Use less wind once, otherwise coal powder will be delayed, and it will cause bureau High temperature.
Wind speed: For coal with high volatile content and low ash content, the primary wind speed can be larger, which can speed up the combustion and increase the flame temperature. For coal with low volatile matter, the speed of the primary air should be lower to avoid the elongation of the black fire head and the high temperature part away from the dense head.
Wind temperature: The temperature of the primary air is high, the pulverized coal is warmed up well, and the flame is short. When the coal volatiles in coal powder are low, the primary air temperature should be controlled higher to accelerate the ignition of coal powder and shorten the black fire head.
4, the influence of kiln exhaust and secondary wind When the
kiln exhaust is unchanged, the primary wind increases, the secondary wind decreases. When the primary air volume is constant, the exhaust at the kiln increases, and the secondary air entering the kiln increases. When the amount of primary air and coal is constant, if the exhaust is increased, the amount of excess air increases, and the flame temperature is lowered. When the primary air does not change, increasing the exhaust and coal consumption while maintaining the same excess air volume, the concentration of pulverized coal in the primary air increases, the flame becomes longer, but the temperature decreases. Increasing the secondary preheating temperature, the flame temperature can be increased, and the black fire head can be shortened.
5 The influence of temperature, raw material and air volume on the flame in the
kiln is low. Even if there is enough air, the pulverized coal can not be completely burned. When the raw material layer is thick or the raw material approaches the kiln head, the flame should be shortened. If the amount of excess air is too much, the flame temperature should be lowered. If it is too small, it may cause incomplete combustion.
6. Influence of material composition The material composition in the
kiln is reasonable, the clinker is finely squashed, and when it is uniform, the tumbling is flexible, the flame shape is good, and the temperature is high. If the composition is unreasonable, if the amount of liquid phase is too large, the firing range is narrow, the bulk is easy to be formed, the flame temperature is increased, or the ring is easy to be formed, and the flame is shortened.
Reasons for high kiln temperature The analysis of the
high kiln temperature is generally caused by the following reasons.
The pulverized coal burns after the combustion of the high temperature zone is insufficient, resulting in a high tail temperature. The pulverized coal has large or fine water content, and the combustion is incomplete in the same time in the firing zone. After entering the transition zone, the combustion continues and the heat is released, and the heat cannot be quickly absorbed by the materials in the kiln, so that the kiln tail The temperature rises.
The amount of pulverized coal is too large, and the wind and coal are properly matched. After the firing zone is burned, the heat released cannot be completely absorbed by the clinker formation, so that the heat required to exceed the clinker formation moves backward with the flow of the high temperature gas to the kiln tail, causing the tail temperature to be too high.
The amount of pulverized coal is extremely large, and in the case where the burnt zone is insufficiently burned by oxygen deficiency, although the secondary wind moves backward and then burns, the temperature of the tail temperature is too high.
The high-temperature fan pulls the wind too much. (The secondary air volume is large, and the third-wind air consumption is also the same.) The wind speed in the kiln is too fast, the distance of the pulverized coal moving in the same unit time is extended, and even the kiln tail part is extended. The combustion caused the tail temperature to be too high.
The internal wind of the burner, the swirling wind, the small amount of primary wind, the large amount of external wind, the long black head, the poor mixing of high temperature and wind coal, the insufficient combustion of pulverized coal, and continued combustion after the transition zone, resulting in excessive tail temperature.
The amount of feed is larger than the actual feed amount. Because the actual material is small, the material cannot absorb heat completely, and the heat that is not absorbed passes through the kiln tail to cause high tail temperature.
The decomposition rate is low, and the heat required in the kiln is high. Due to the slow heat transfer rate in the kiln, the heat in the kiln cannot be absorbed quickly, resulting in a high tail temperature.
Measures to be solved:
In the operation, the wind, coal and materials should be well coordinated, and the fineness of the coal powder should be properly controlled to ensure that the coal powder can be fully burned in the firing zone.
Adjust the burner, mix the inner and outer winds and the swirling wind to shorten the burning time of the coal powder. Improve the apparent decomposition rate of raw materials into the kiln.
Analysis of the reason why the tail temperature is high and the kiln current is low
1. If the tail coal is excessively added, and the secondary air temperature is not enough (such as about 900), then the combustion of the tail coal is not complete, which will increase the temperature of the smoke chamber; If the head coal is added too much, the sulfur content will increase, making the kiln easy to ring, the ventilation is not good, and the tail temperature is also affected. 3. The clinker failure and the low kiln current may be caused by the ingredients. The saturation ratio is high, and the raw material is relatively hot, resulting in insufficient liquid phase, so the kiln current will be low, and the clinker free calcium is also high.
Solution: Look at the smoke chamber, rising flue, etc. Whether there is skinning, the temperature of the decomposition furnace is high, and there is an exothermic reaction after the material is down. The tail temperature will rise, and the liquid phase will appear in advance to see if the material is owed. Burn or have a yellow heart. The crust should be removed in time, the ventilation in the kiln should be strengthened, the fineness and moisture of the pulverized coal should be reduced, and the amount of coal should be controlled to prevent the reduction reaction. Appropriately increase the opening degree of the third damper, reduce the wind in the kiln, shorten the length of the flame, control the fineness of the pulverized coal and the amount of heat generated. Reduce the raw material KH and increase the amount of liquid phase appropriately.
Prevention and treatment measures for kiln tail ring
1. Mechanism of formation of the ring
When the temperature of the material in the kiln reaches about 1250 °C, the liquid phase will appear in the material (as the temperature increases, the viscosity increases under the action of C3A. Under the action of C4AF, the amount of liquid phase increases, and the viscosity of the material becomes smaller as the liquid phase increases. The temperature of the kiln lining exposed to the hot air flow is always higher than the temperature of the material in the kiln. When he is covered by the material layer, the temperature suddenly drops, and the liquid phase of the heat dissipation on the surface of the kiln cylinder solidifies on the kiln lining to form a new kiln. The skin, to continue to operate, the kiln skin is exposed to the high-temperature hot air stream and is melted and dropped. When he is covered again by the material, the liquid phase solidifies again, and so on. The more kiln skin is thicker and thicker, and as the kiln skin continues to thicken, the temperature of the surface of the kiln skin increases continuously, and the viscosity of the liquid phase gradually decreases. If the process reaches equilibrium, the kiln skin will not thicken, which is normal. If there is less drop on the bond, the kiln skin will be thicker, and vice versa. When the kiln skin is thickened to a certain extent, a circle is formed.
Second, the phenomenon
occurs after the formation of the ring, the negative pressure of the kiln head is reduced, and even positive pressure occurs, the negative pressure of the kiln tail smoke chamber increases, and the unsteady material of the kiln clinker appears one-and-one. At the same time, the flame is not smooth, the temperature of the high temperature belt rises, the load of the kiln increases significantly, and the speed and the amount of material are not matched, and the operation is difficult to control. The outside temperature of the cylinder at the knot is greatly reduced. When it is serious, it is close to the outdoor temperature, and the kiln seal ring has a general phenomenon. Through the formation process of the above kiln skin to the ring formation process, we can judge that the ring formation is caused by breaking the equilibrium growth process of the kiln skin inside the kiln.
Third, the cause analysis
1 The feed quantity is unstable, which is easy to cause
a natural balance point in the production and falling off of the kiln skin during the calcination process. This is the minimum eutectic temperature of the material and the critical point of the kiln temperature. It is assumed that the position and temperature of the liquid phase appearing are constant under all conditions, and the growth and shedding of the kiln skin are balanced, and it is impossible to cause a loop. However, the instability of the incoming material will be small and small, which will break the balance of the growth and shedding of the kiln skin and cause the ring. The material is first moved to the lowest co-melting point, and the temperature of the material in the molten liquid phase is lowered at the same position. The temperature difference of the covered kiln lining is large, and the material is easily solidified on the kiln lining to form the kiln skin, and is exposed to When the hot air is in the air, it is not easy to be burned, thereby breaking the balance and causing the ring.
2. Fluctuation ofFluctuation of
raw meal compositionraw meal composition directly affects the change in liquid phase and liquid phase viscosity, as well as the temperature of the flame and the burning position of the flame. The change of liquid phase and liquid phase viscosity undoubtedly directly breaks the balance between kiln skin growth and shedding, which is an important factor in the formation of the ring; the heat absorption of the material due to the fluctuation of the raw material affects the length and position of the flame. Also, the change in the position of the eutectic point affects the balance between growth and shedding of the kiln.
3. Influence of
trace elements Trace elements are easy to cause ring formation. Under normal conditions, the minimum eutectic temperature of raw meal is about 1250 °C. When CaSO4, K2SO4 and Na2SO4 coexist, the minimum eutectic temperature may be lower than 800 °C; When the compound is present, the minimum eutectic temperature can approach 700 °C; once the trace elements fluctuate, the liquid phase will have large fluctuations in the co-melting position, which will help the formation of the ring.
4. Changes inquality The change
coalin the calorific value of coal directly affects the change in temperature in the kiln. The change in temperature directly affects the position where the liquid phase appears, thus contributing to the formation of the ring. The change of coal ash will directly affect the change of clinker composition, and will also affect the stability of trace elements in clinker, which will affect the temperature of clinker formation and provide opportunities for the complete set.
Factors affecting the flame length of the rotary kiln: What is
the relationship between the main motor current of the kiln and the kiln system:
1. The kiln drive current trajectory The flat kiln drive current (or torque) is very stable, and the traces depicted are very flat. It shows that the kiln system is very stable and the thermal system is very stable.
2, kiln drive current track The fine kiln drive current (or torque) traces very fine, indicating that the kiln skin in the kiln is flat or uneven, but the torque applied to the kiln during the kiln rotation is balanced.
3, kiln drive current trajectory The rough kiln drive current (or torque) depicts a very thick trajectory, indicating that the kiln skin is not flat, during the rotation process, the torque generated by the kiln skin changes periodically.
4. The kiln drive current suddenly rises and then gradually decreases. The transmission current (or torque) suddenly rises and then gradually decreases, indicating that there is a kiln skin or a kiln ring in the kiln. If the increase is large, the more kiln skin or kiln ring is fallen, most of the sag occurs between the kiln mouth and the firing zone. When this happens, the kiln speed should be reduced immediately according to the amplitude of the curve rise (if the kiln drive current or torque rises by about 20%, the kiln speed should be reduced by about 30%), and the feed amount and the decomposition furnace fuel should be appropriately reduced, and then Take further action based on the rate at which the curve slips. At this time, the cooling machine should also adjust the speed of the south plate. After the curve turns, the kiln speed, the feed amount, the decomposition furnace fuel, etc. are gradually increased to make the kiln transfer to normal. In case of such improper treatment, there will be adverse consequences such as raw material burning, chiller overload and excessive temperature damage to the raft.
5, kiln drive current (or torque) is high, there are four cases can cause this result.
First, the kiln is overheated, the firing zone is long, and the material is carried high in the kiln. At this point, reduce system fuel or increase feed. Second, the kiln produces a kiln ring and a high filling rate of the material in the kiln, which causes the material to be poorly granulated, and the dust returning from the chiller to the kiln increases. In this case, the feed amount should be appropriately reduced and measures should be taken to burn off the front ring. Third, the material has poor pelleting properties. Due to various reasons, the mature material is newly dispersed, and the material turns from rolling to sliding, making the kiln difficult to rotate. Fourth, the kiln skin is thick and the kiln skin is long. At this time, it is necessary to shorten the flame and press the firing zone.
6. The kiln drive current (or torque) is very low. There are three conditions that can cause this result.
First, the kiln is not burning seriously, and it is close to running raw materials. In general, when the transmission current (or torque) is lower than the normal value and there is a downward trend, measures should be taken to prevent further decline. Second, there is a rear ring in the kiln. After the material accumulates to a certain extent after the circle, it is rushed into the firing zone through the ring, resulting in a short firing zone, a quick burning of the material, and easy to form a large block. Clinker is more yellow, and free calcium is also high (sometimes up to 10%). At this time, since the firing zone has a small amount of fine material, the firing temperature displayed by the meter is generally high. In this case, the material should be reduced and the rear ring should be disposed of third. The kiln skin is thin and short. At this time, the flame should be extended and the firing zone should be extended appropriately.
7. There are three reasons for the gradual increase of the kiln drive current.
First, the kiln develops toward a high temperature. If the original clinker is not burning, it means that the kiln is becoming normal; if the original kiln is burnt normally, it indicates that the kiln is getting too hot, and should be adjusted by feeding or reducing fuel. Second, the kiln begins to lengthen the kiln ring, the material filling rate is gradually increasing, and the firing zone or bulk material is increasing. Third, long and thick kiln skin is forming.
8. There are two reasons for the kiln drive current to gradually decrease. First, the development of the kiln in the direction of lower temperature, the addition or reduction of fuel may produce this result. Second, as mentioned earlier, this can also occur with an increase in the amount of unloading after the kiln skin or front ring has fallen.
9. There are also two reasons for the sudden drop in the kiln drive current. First, the preheater and the decomposition furnace system collapsed, and a large amount of un-burned materials suddenly poured into the kiln, causing the belts to move forward and burn in front of the kiln. At this time, measures should be taken to reduce the speed of the kiln and appropriately reduce the amount of feed, and gradually return to normal. Second, the large crust falls off the slope of the kiln, blocking the material, and after a certain amount of “suddenly entering the kiln suddenly, it has the same effect as the first case. At the same time, the large crust also hinders the ventilation, and the fuel does not burn. Well, the low system temperature will also make the kiln drive current low. It depends on the kiln drive current for operation, and has the advantages of clear, timely and reliable information, especially combined with parameters such as firing temperature, kiln temperature, system negative pressure and exhaust gas analysis. It is better to judge the condition and change in the kiln accurately, and it is impossible to reflect the kiln condition so completely and accurately by relying on any other parameters alone. For example, the temperature of the firing zone can only reflect the situation of the firing zone, and it is extremely easy. affected dust and flame while the kiln current (or torque) was timely reflect the condition of the firing zone, where about half an hour indicating the burning zone, prompt the operator to make the necessary adjustments.
calciner blockage And preventive measures
1. Analysis of theblockage The factors
cause ofcausing crust, accumulation and blockage of the new dry precalcining kiln tail system are many and very complicated, and should be from the process, The raw materials, equipment, thermal system, operation and management are analyzed and studied. According to the analysis of the blockage caused by the production line, the following aspects are generally caused.
1 . The clogged skin caused by
crust is high temperature material in the smoke chamber , rising pipeline, all levels (mainly third, fourth) on the inner wall of the cone of the cyclone cone, a layer of hard skin, the serious place is ring-shaped shrinkage, hindering the normal operation of the material, bonding and melting Alternating, the number and thickness of the cortex gradually increase, affecting the ventilation in the kiln, changing the running speed and direction of the material and airflow in the preheater, and finally causing blockage. There are three main reasons for this phenomenon:
(1) The effect of ash return
The material collected by the electric dust collection (including the humidification tower) has undergone high temperature physical and chemical reaction. When the material re-enters the preheater, it is easy to cause the material to decompose early, and the liquid phase appears in advance, and it is too late to reach the kiln. The molten material forms a molten state and adheres to the inner wall of the cyclone barrel to form a crust, which causes blockage in severe cases. This situation is mainly caused by high temperature in the kiln tail system and no ash incorporation. When the amount of uniformity or the amount of incorporation is too large, the dust collection efficiency of the cyclone dust collector is not high, and the electric dust collection is not returned to the raw material storage homogenization system, but directly into the kiln from the lift pump. Or when there is no stable metering facility or the failure of such facilities, the operation should be strengthened to prevent high temperature. It is also necessary to adjust and modify the ash-incorporating system. Improve the system cyclone, especially the top. The dust collection efficiency of the cyclone dust collector reduces the dust content of the electric dust collection to reduce the ash return.
(2) The influence
of harmful elements on the high content of harmful elements such as K, Na, Cl, S in the original fuel, a large amount of alkali It will evaporate from the high temperature zone of the firing zone, enter the gas phase and react with other components, first react with chlorine and sulfur dioxide, and bring it to the kiln tail system with the gas flow. After the temperature is lowered, it will be condensed in the form of sulfate and chloride. The precipitate forms a molten phase at a lower temperature to form a fine melt, and then solid particles are consolidated. They pass through multiple high temperature volatilization, low temperature condensation cycle and adhesion, and adhesion. The preheater, calciner and formed in the coupling pipe crust, if not treated promptly, the cycle continues adhesion, resulting in clogging.
(3) The local high temperature causes the crust to block the
pre-decomposition system, and the temperature is high, which leads to more factors of crust. If the flow fluctuations; coal powder due to incomplete combustion into the preheater to produce secondary combustion; system operation instability, etc. will lead to local high temperature, so that the liquid phase appears in advance, forming a cohesive material crust. The flow is suddenly large and small, and it is easy to disturb the normal operation of the preheater, the decomposition furnace and the kiln. The operation often lags behind, can not keep up with the change of the flow, adding or subtracting coal is not timely, and even short-term breakage, can not reduce coal in time, resulting in less system temperature due to less material, causing skinning and blockage. During ignition, due to incomplete combustion of pulverized coal in the kiln or in the decomposition furnace, part of it ran into the preheater and attached to the cone and the discharge pipe. When the temperature rises, it ignites and forms a local high temperature. In operation, the one-sided surface emphasizes the decomposition rate of the kiln, the coal used in the decomposition furnace is too large, and the proportion of the two fires is out of balance, resulting in a high temperature in the furnace, a liquid phase prematurely occurring, and the tangential speed of the material in the furnace is high, and the centrifugal force is large, very It is easy to cause the molten material to adhere to the furnace wall to form the crust in the furnace; because the residence time of the material in the decomposition furnace is extremely short, the excessive pulverized coal can not be burned in the furnace, and is brought to the fourth-stage cyclone to form secondary combustion. Causes the temperature inside the cyclone to be too high.
2, . The air leakage caused by
air leakage is a large nemesis of the kiln decomposition kiln. It not only reduces the separation efficiency of the cyclone, but also increases the heat consumption, which is a major factor causing system blockage.
(1) Theis blocked by the internal air leakage, which is
ash discharge valve of the pre-heater discharge pipe of each stagenot tightly closed, burned out or malfunctions, and can not play a good role in locking air. Not only the efficiency of the dust collection of the cyclone is reduced, but also Short circuit, collapse and blockage. Because the air discharge valve of the blanking pipe is not tightly locked, the next gas will pass through the blanking pipe, so that the materials collected in the preheater will rise again and cannot be discharged smoothly, resulting in internal circulation. Since the wind speed at the feed opening is high and does not reach a certain amount, the material will not settle. However, once the material has too much sedimentation condition, it is a large drop, resulting in uneven feeding, poor dispersion, resulting in blockage. .
(2) Blockage caused by
external air leakage The external air leakage refers to the cold air that leaks into the system from outside the system. It mainly leaks from the inspection door of each level of the cyclone, the discharge valve shaft of the discharge pipe, the flange of each connection pipe, the top cover of the preheater, and various measurement points. The airflow movement in the cyclone preheater is complicated, and the particle size distribution of the powder is wide, which makes the internal material movement more complicated and random. If the system is not well sealed, the cold air is leaked, the trajectory of the material in the preheater is changed, the rotational speed of the material is reduced, the centrifugal force of the centrifugal ramming wall is reduced, and some materials return to the upper stage with the airflow, causing material circulation. And eventually piled up. On the other hand, when the cold air leaks into contact with the hot material, it is easy to cause the material to coexist cold and heat, adhere to the wall of the preheater cylinder, causing crusts or large chunks, and jamming the lowering pipe or the ash discharging valve causes blockage. . In addition, when the fuel is not completely burned, the combustibles and the leaked O2 are re-burned, causing local high temperature, and the superheat causes the material to melt and adhere on the inner wall, and the crust is clogged.
3, the blockage caused by improper operation
(1) is not timely. When the decomposition furnace is ignited and the feed temperature is reached, it must be fed in time, otherwise the system temperature will be high, and therefore the amount of material is small, which is more likely to cause skinning.
(2) The amount of exhaust air is improper when starting and stopping the kiln. When it is necessary to stop the material and stop the kiln, the exhaust air volume cannot be reduced by a large degree of radiation, otherwise it is easy to cause the material to be deposited in the pipe due to the excessive wind speed (mainly in the horizontal pipe), causing accumulation. When the kiln is re-opened, the amount of exhaust air is too small, and the accumulated materials cannot be taken away smoothly. As the amount of material is continuously increased, the accumulation of materials in the pipe increases, and in a serious case, it may cause blockage.
(3) The amount of material to be discharged is not synchronized with the speed of the kiln. The operation of the kiln is not normal, the thermal system is unstable, and it is necessary to pre-play the small slow speed or the slow rotation kiln. It is easy to reduce the material and the kiln speed is not synchronized, which causes the materials to accumulate in the kiln exhaust chamber. At this time, even if the kiln is still running, the material accumulated at the end of the kiln cannot be quickly transported out. The accumulated material is melted and adhered to the inner wall of the kiln exhaust by high temperature, forming a shed phenomenon at the junction of the kiln and the kiln, resulting in a shed phenomenon. The smoke chamber and the upper preheater are blocked.
(4) The air volume is not properly controlled. When the exhaust air volume is too large, the airflow speed of the pre-decomposition system is high, the centrifugal force of the material being rubbed toward the wall surface in the preheater is large, the falling speed of the material along the wall surface is reduced, the contact time of the material with the high-temperature airflow is relatively long, and the viscosity is easy to stick. Paste on the inner wall of the preheater to form a layered covering from loose to solid, causing clogging; when the exhaust air volume is too small, the airflow speed is reduced, it is difficult to disperse the mass, forming a collapse of the material, and the material is easily retained. In the horizontal connection pipe, the horizontal pipe is blocked.
(5) The distribution of kiln and furnace air volume is uneven and the operation is not coordinated. The operation adjustment is unreasonable, the opening degree of the kiln end shrinkage ram and the opening of the tertiary damper into the decomposition furnace are not correct, which may lead to uneven distribution of the kiln air volume. If the wind speed of the kiln tail is too low, or the wind speed of the decomposition furnace inlet is too low or too high, it will cause the material to crust, shed, collapse, and accumulate in the pre-decomposition system until it is blocked. Kiln and furnace operation can not be considered before and after; coordination is not good; one-sided emphasis on kiln ventilation, system negative pressure; improper pursuit of kiln decomposition rate, two fires are not well matched, but also easy to cause high temperature crust, accumulation, collapse Blocked.
4,of the blockagecaused by foreign objects
the inspectionsystemdoes not work out; the cyclone, the top cover of the decomposition furnace and the lining material are peeled off; the inner cylinder or the scattering plate of the cyclone is burnt down; the ash valve is burnt Bad or unsatisfactory; refractory bricks or irons and other items remain in the preheater during maintenance and are prone to mechanical blockage of the preheater.