What should be done when the limestone vertical mill is insulated

What should be done when the limestone vertical mill is insulated by the kiln fire?

In the process of limestone grinding production, it is inevitable that there will be two mechanical or technological reasons leading to the suspension of the fire in the vertical grinding. In order to avoid the damage of the kiln skin caused by the large temperature change caused by the kiln head ceasefire and ignition, the decomposition is generally used. The furnace is stopped and the kiln is fed with 23.5T/H coal to ensure the temperature in the kiln.


If the stock of the vertical mill is less than 25 m at this time (the full warehouse is 40 m), the exhaust gas from the kiln tail will be used to provide heat source for the raw mill for production. The specific method is: the valve 3210 is fully open, the opening degree of the valve 3213 can be adjusted according to the inlet temperature of the vertical mill and the circulating material in the vertical mill. The inlet temperature is high and the circulating material quantity is large, then the valve 3213 opens two points. On the contrary, it will open a small two points, and its opening degree is generally 40% and 95%. The opening degree of the valve in front of the high-temperature fan and the valve 3409 in front of the rear exhaust fan depends on C, the temperature at the outlet of the cylinder and the negative pressure. C, the outlet temperature of the cylinder is controlled to be less than 380 ° C, C. The negative pressure of the barrel outlet is controlled between two 600 and two 900 Pa. In the general case, the valve opening degree in front of the high temperature fan is about 10%, and the opening degree of 3409 is about 10% to 15%. If the two valves are opened too much, the ventilation in the kiln is increased, so that the heat loss in the kiln is increased, and the kiln is not well insulated. Most of the heat is pumped into the kiln exhaust chamber and the preheater. The temperature rises there and is prone to crusts. If the two valves are too small, the ventilation in the kiln will be insufficient, which will affect the combustion of the coal in the kiln. Valve 3407 should be shut down, valve 3212 should also be shut down. Under the premise of ensuring the micro-negative pressure of the high-temperature fan outlet (two 20 to two 50 Pa), the valve 3202 should be opened as much as possible, and it is better to open it all. The purpose is to Let the hot air coming out of the kiln pass through the limestone vertical mill to dry the materials in the vertical mill.

What needs to be mentioned is that if the limestone vertical mill is to be baked in the winter because of the low external temperature, it can be baked in the order of 32% and 20% in advance, and the opening is too small to achieve the purpose of drying. The material that has passed through the mill will be taken away by the wind. The temperature of the kiln exhaust gas from the humidification tower is controlled at about 270 °C, which can be controlled by adjusting the water pump pressure in the humidification tower, and the air temperature reaching the vertical mill inlet is about 230 °C. In this case, since the amount of hot air in the vertical mill operation is limited (the valve opening degree is limited before the high temperature fan), the amount of air entering the mill is small, and the total amount of wind entering the mill stroke is small. The heat is also less than normal. Therefore, the amount of feed should be reduced accordingly. The normal feeding amount is about 155 t/h, and at this time, only the feeding amount of about 130 to 140 t/h can be fed. The outlet temperature of the mill is also lower than normal, and is normally about 90 to 95 °C. The outlet temperature is now controlled at about 65 to 80 °C. The pressure difference at normal time is about 5.3 KPa, and the pressure difference is controlled at about 4.7 KPa. The mill current is originally 90 to 100 A, and is now 81 to 93 A. Normally, the inlet negative pressure is controlled between two 300 and two 500 Pa, and the inlet negative pressure reaches 900 l (000 Pa;

Since the inlet air volume and the inlet temperature of the mill are stable compared with the hot air furnace in this state, the vertical mill operation is much more stable than that of the hot air stove, which greatly reduces the inlet temperature when the hot air stove is heated. The fluctuations cause the vibration caused by the instability of the inner layer of the mill. At the same time, it also reduces the chance of the components in the mill being damaged, thus ensuring the long-term safe and stable operation of the mill. At this time, the vertical grinding not only has a stable feeding amount but also increases the output time when the hot air furnace is heated (the production time at the time of burning the hot air furnace is about 110 t/h). This minimizes the chance of using a hot blast stove to operate the vertical mill.

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