What are the criteria for determining the upward movement of the calcination zone in a lime kiln
It is crucial to accurately determine whether the position of the calcination zone has shifted upward during the production and operation of the lime kiln, which is related to the quality of lime, production efficiency, and safe and stable operation of equipment. The following are some main criteria for determining the upward movement of the calcination zone in a lime kiln:
1、 Temperature variation characteristics
Temperature is one of the most intuitive indicators reflecting the position of the calcination zone inside the lime kiln.
Abnormal increase in top temperature: When the calcination zone moves up, the kiln top temperature usually shows a significant upward trend. Under normal circumstances, the top temperature of the kiln is within a relatively stable range, but if the top temperature continues to rise beyond the normal value, such as rising to 280 ℃ or even higher and remaining high, this is likely a signal of upward movement of the calcination zone. Because when the calcination zone is close to the top of the kiln, the released heat will accumulate more in the top area, resulting in an increase in top temperature.
Changes in temperature distribution in each zone: In addition to the top temperature, attention should also be paid to the temperature distribution in different areas of the kiln. The upward movement of the calcination zone will gradually decrease the temperature of the lower calcination zone and cooling zone, and the stable temperature that was originally maintained in these areas will decrease due to the upward movement of heat. At the same time, the temperature of the preheating zone and the upper calcination zone will gradually increase. This pattern of temperature fluctuations in different regions is an important temperature criterion for determining the upward movement of the calcination zone.
2、 The state of lime blocks
The state of lime blocks discharged from the lime kiln can also provide clues for determining the upward movement of the calcination zone.
Temperature sensation: When touching the discharged lime block with your hand, if it feels cool, it is significantly different from the lime block that has been fully calcined and has a suitable temperature. Normally, the normally calcined lime blocks have a certain residual temperature, but when the calcination zone moves up, the lime is not fully heated in the kiln, resulting in a lower temperature after discharge and presenting a cooling state.
Surface features: Careful observation of the surface of the lime block will reveal some special signs. The upward movement of the calcination zone may cause irregular erosion and peeling of the surface of the lime block due to wind blowing. This is because during the calcination process, the change in position causes a change in the environment in which the lime block is located, which may be affected by abnormal airflow or temperature fluctuations, leaving these characteristic marks on the surface.
3、 Abnormal production parameters
Some parameter changes during the lime kiln production process can also assist in determining the upward movement of the calcination zone.
The relationship between ash output and air volume: If the ash output continues to be low while the air volume is relatively high, this is a dangerous signal that may prompt the calcination belt to move upward. A low amount of ash discharge means that the material in the kiln decreases slowly, and the heat cannot be evenly distributed with the smooth descent of the material, which is prone to accumulate in the upper part of the kiln. In addition, the large air volume further disrupts the heat distribution, causing the position of the calcination zone to move up.
Coke particle size and coke powder situation: As an important fuel for lime kilns, coke particle size and coke powder content are also related to the position of the calcination zone. When the particle size of coke is too small and there is a lot of coke powder, its combustion characteristics change, and the heat release is not uniform and stable enough, which may lead to abnormal upward movement of the calcination zone position. Therefore, if it is found that the coke particle size and coke powder situation do not meet the normal production requirements, and are accompanied by abnormal phenomena such as temperature and lime blocks, the possibility of upward movement of the calcination zone needs to be considered.
4、 Equipment operation feedback
The operating status and feedback information of lime kiln related equipment can also help determine the upward movement of the calcination zone.
The temperature of the kiln roof equipment is too high: The kiln roof is usually equipped with various devices such as temperature sensors, ventilation ducts, etc. When the calcination belt is moved up, the ambient temperature of the kiln top equipment will increase, which may cause these equipment to have excessively high temperatures. For example, temperature sensors may frequently alarm, indicating that the temperature exceeds the normal range, which indirectly reflects the upward movement of the calcination zone.
Changes in ventilation effect: Moving the calcination belt upwards may affect the ventilation effect inside the kiln. If poor ventilation is found, such as abnormal airflow velocity and unstable pressure in the ventilation duct, it may be due to a change in the position of the calcination zone, uneven heat distribution, which affects the normal operation of the ventilation system and can also be used as a reference for judging the upward movement of the calcination zone.
Through comprehensive observation and analysis of temperature change characteristics, lime block status, abnormal production parameters, and equipment operation feedback, we can accurately determine whether the calcination zone of the lime kiln has moved upward, and take corresponding adjustment measures in a timely manner to ensure the normal production and efficient operation of the lime kiln.
