Clinker kiln (cement kiln or cement rotary kiln) is the main equipment of cement plant. The clinker is formed by calcination in it. During the calcination process, raw meal powder is fed into the kiln cylinder from the top of the kiln tail. Due to the inclination and gentle rotation of the kiln cylinder, materials produce a compound movement which not only rolls along the circumference direction but also moves along the axis from the high end to the low end. They will be composed and sintered in the kiln and finally forming clinker, being discharged from the bottom of the kiln cylinder and entering the cooler. Fuel is usually injected from the kiln head and burned inside the kiln. The heat emitted in this process will be used to heat raw materials to achieve the calcination effect. The hot air formed during the heat exchange with the material will enter the kiln system at the feed end, and then be discharged into the atmosphere by the chimney.
Calcining Technology of Clinker
Control the Negative Pressure and Airflow Velocity in Clinker Kiln
The control of negative pressure is very important for clinker calcination. We usually install a negative pressure measuring device at the end of the cement kiln. The negative pressure generated at the end will be directly displayed on the operating instrument panel mounted at the kiln head by the transmitter. Here is a very important point that we have to mention. That is the change of negative pressure will indicate the corresponding change of air velocity in the clinker kiln. In addition, if the air velocity in the clinker kiln is controlled stably, the calcination condition of the kiln will be good, so the control of air velocity is also a key factor affecting the performance of the cement rotary kiln. During the operation of cement kiln, if the flow rate is relatively fast, the fuel injected into the kiln cylinder will be sent to the kiln tail or air chamber before it is completely burned. In the case of high temperature in the air chamber, it will be disadvantageous to the calcination process. And when the temperature of sintering zone is lower, the normal thermal regulation of cement kiln will be affected correspondingly, a lot of heat will be lost, which will result in the decrease of clinker quality and output. In addition, if you are familiar with the calcination process of cement rotary kiln, you will know that when the temperature of the air chamber is too high, it will also affect its structure, threaten the firmness of the building, and in serious cases, the vault of the air chamber will collapse. Therefore, the real-time monitoring of air chamber temperature is also very important.
The Influence of Coal Quality on Clinker Calcining
Generally, the quality of coal for calcination in clinker kiln requires that ash content A is less than 30%, volatile component V is between 18%-30%, calorific value QDW is more than 5000kcal/kg, and the fineness of pulverized coal is controlled at 8%-15%. What’s more, the proportion of coal used in decomposition furnace at kiln tail and injected at kiln head should be controlled at 6:4 to increase the mixing degree of coal ash with raw materials in decomposition furnace and reduce the negative influence of coal ash on clinker quality. Secondly, we should control the feeding coal quality at decomposition furnace and kiln head respectively. That is Feeding low calorific value coal in decomposition furnace and high calorific value coal in kiln head. This method can reduce the adverse effect of low quality coal on clinker.
Clinker is the main component of cement. Only when the output of clinker is high, the output of cement will increase accordingly. And when the clinker strength is high, mixtures are added more, which can also increase the output of cement and reduce the cost and heat consumption. So the calcination of cement clinker is the key process of cement production. Among them, clinker kiln as the clinker production equipment is the core of the whole cement production line. Both its quality and manufacturing technology have a direct impact on cement products, so the choice of clinker kiln is very important for cement manufacturers. AGICO, as one of the leading cement plant and cement equipment suppliers in China, provides high-quality rotary kilns, crushing mill, grinding mill, etc. We also offer cement plant design service, equipment installation and commissioning service and after-sales service. If you are interested in our products, please feel free to contact us!
In the above content, we mainly talk about controlling the negative pressure and airflow velocity in clinker kiln and the influence of coal quality on clinker calcining. In the article The Calcining Technology Of Clinker Kiln 2, we’ll go on to discuss that.