Operation skill of cement rotary kilnDate: 2019-07-26 Views:
In the process operation of rotary kiln in cement plant, many problems are often encountered.We summarized some operating methods and experience, now summarized as follows, together with peers to discuss and study.
1. Ignition operation
No matter it is newly built or put into production after maintenance, ignition will be encountered. Before ignition, the whole firing system should be tested jointly, so as to avoid the occurrence of bad working conditions such as high temperature of the preheater system, blockage of the cyclone tube and the feeding pipe caused by equipment glitches during feeding.Whether it's wood or diesel fuel.All high temperature fan doors should be closed, as appropriate to open the ignition chimney, rotary kiln head is a state of micro negative pressure, in case the wind is too large and not easy to ignite.In the injection of pulverized coal should try to ensure the pulverized coal burnout rate, can not spray too much, slowly add coal;Kiln should be rotated at a certain interval of I/4 each time to avoid bending deformation of the cylinder.When the temperature reaches more than 700C, the application of auxiliary continuous rotary kiln, according to the situation to start the high temperature fan, the appropriate adjustment of the wind door opening;When the temperature reaches 900V, the main rotary kiln can be used.If the ignition with diesel oil should not be busy all shut down the oil pump, but can be appropriately adjusted small valve opening;The oil supply can not be stopped until the material reaches the firing belt after feeding.When feeding, should be based on kiln end temperature and preheater outlet temperature to determine;The feeding amount of rotary kiln should be relatively high at the beginning, generally not less than 60% of the designed output, and then slowly increase the feeding amount, and the feeding range should be small but not large, until the normal feeding amount;In addition, the running time at low feed rates should be minimized, as it is very easy to collapse during this period and cause clogging of the preheater system.
2. Operation of hanging kiln skin
After brick replacement (here only refers to the firing belt), the kiln operation should be properly carried out, avoid temperature rise.First of all, hanging kiln skin has certain requirements on raw material composition, especially the amount of liquid phase and the refractoriness of materials.Liquid volume is easy to form kiln skin, but also easy to collapse, not firm, can not withstand high temperature ship burning;If the amount of liquid phase is small, refractory materials, it is difficult to form the kiln skin, the formed kiln skin is quite strong, but if there is collapse, it is not easy to fill.According to our years of experience, when hanging the kiln skin, the raw material powder used in normal production is usually better, which is beneficial to the formation of kiln skin.Because the kiln skin is a dynamic balance in the process of boring burning, even if a small part of the collapse is easy to timely replacement, but during the cement rotary kiln hanging kiln skin do not run raw materials and underburning phenomenon.
3. Formation and treatment of flying sand
There are three main reasons for the formation of flying sand.First, improper raw material ingredients lead to high silicon rate SM, high aluminum rate IM, and low iron content, which leads to low liquid volume and increased liquid viscosity in the firing process, making it difficult to form calcium silicate (C3S), thus forming flying sand.Second, some manufacturers in order to reduce costs, with volcanic ash fly ash calibration raw materials, also easy to form fly sand;Third, the cooling machine effect is not good, and the formation of flying sand.
When flying sand material, someone to open large exhaust air, improve the kiln end temperature.In my opinion, opening large exhaust air can indeed enhance the prefiring performance of materials. However, when the materials reach the solid phase reaction zone, the liquid content of materials is not enough, and it is difficult to granulation when the firing zone is formed. In this way, it is easier to form flying sand materials, and it will affect the stability of the kiln skin of the whole firing zone, which is not good for the kiln condition and thermal system.Through several years of practice and exploration, we take the measure is to exit the coal injection pipe, and appropriately turn down the exhaust air volume (serious can be appropriate
When reduce production), use short flame eager to burn, reduce the temperature of the preheater, presintering effect, to reduce the material to make the liquid volume in the burning brings and the formation of more effective C3S formation, it is not able to completely avoid the formation of fly sand material, but it can effectively reduce or weaken the fly sand material, and in addition to the part of front-end for kiln kiln skin damage, will not affect the whole stability of calcining zone of the kiln's skin, after being improved raw ingredients can make up.
4. Unstable handling of incoming materials
In normal production, the amount of raw material is fluctuated, but the fluctuation range is small.However, when the cement rotary kiln equipment has some problems, or the raw material moisture is not easy to control in the rainy season, the raw material is likely to agglomerate on the top or wall of the warehouse, resulting in poor discharge, there will be a large fluctuation range.In this case, the operator is required to observe frequently, frequently adjust, and have a certain predictability.According to the current changes of some conveying equipment to determine the amount of material.Take action in advance to reduce adverse impact on production, quality and equipment.
(1) when the less material, avoid by all means will stretch into a pulverized coal burner, a big wind, stretched flame, it can make the preheater, the temperature rise sharply, decomposing furnace, the temperature of the cyclone tube will soon rise, thus easy to cause discharging pipe of cyclone tube or adhesive blockage, even preheater smoke chamber and decomposition furnace also easy crust, and make the system resistance increases.When the material quantity is small, the correct operation method is as follows: push the coal spraying pipe back, turn down the exhaust air, reduce the coal feeding quantity of the decomposition furnace and the kiln head, control the temperature of the kiln tail and the temperature of the cyclone tube, use the short flame to burn rapidly, and wait for the arrival of the material.
(2) when there is a large amount of incoming materials, positive pressure will appear in the kiln head, and the temperature of cyclone tube outlet, decomposition furnace and kiln tail will drop sharply. At this time, the kiln speed should be appropriately reduced, the quantity of feeding should be reduced, large exhaust air should be opened, and the coal spraying pipe should be put in, so as to increase the temperature of kiln tail and enhance the effect of pre-burning of materials.Coal can also be added appropriately, but not too much, or it will cause reducing atmosphere, making the temperature in the kiln lower.When the current of the kiln main transmission motor decreases rapidly, the kiln speed should be reduced, the coal spraying pipe should be withdrawn, and the exhaust air volume should be adjusted appropriately. At this time, short flame and rapid combustion can be adopted to restore the normal.When the working conditions in the kiln are normal, the feeding should be carried out again, and the temperature should not be raised by feeding. This will make the operation in a passive state, and the production and quality can hardly be guaranteed.