Preheater drying material selection and preparation before ignition

Update: 30-09-2019

The refractory materials used in the preheater are refr […]

The refractory materials used in the preheater are refractory bricks and fire mud, and the moisture in the fire mud is also relatively high. Because the refractory material of the preheater is static and less damaged, only the new kiln has a preheating machine. The goal of the drying process is to make the temperature measurement point temperature in the uppermost cyclone above 100 ° ° C. It can be inferred that it is no longer wet in the fire brick inside the preheater.
1. Before drying, all the equipment needed to prepare the tools, fuel, etc. to dry the preheater must be prepared. The preheating machine is usually prepared by using a diesel burner. Because diesel has low viscosity, good atomization, good flammability, no need for heating, but the price is more expensive, the oil is sprayed out and burned by pressure spray. The manhole of the preheater feed chamber is used as the burner. The burner of the open position burner has inner and outer rings. The outer ring is used for primary air input. At the end of the injector, a certain angle of the sheet is provided, so that the diesel fuel and the air can be better mixed by the inner ring, and the entire fuel injection end has five sets of nozzles for fuel injection. The amount of fuel injection is about 5% at the time of normal combustion, and the range of fuel injection adjustment is about 10% of the total oil amount, and the amount of oil is increased quantitatively and evenly. The air during fuel injection is supplied by a special primary air windmill. The air volume required for preheating is 30m3/min and the wind pressure is 500mmAg. Diesel is delivered after being pressurized by a pressure regulating rotary pump.
2 Preparation before ignition
Before the preheating machine is ignited, keep the air ducts in the preheater unobstructed, open all the cyclone cylinder discharge valves, and remove the foreign matter inside the air duct, so as to avoid the remaining items left in the project and affect the operation. All the inspection holes and cleaning holes of the preheater should be closed, so that the water in the brick and the fire mud is discharged with the exhaust gas. Open the preheater windmill to maintain a certain negative pressure inside.
3. Drying of the preheater
In the preheater, there is more fire mud in the refractory material, and more water is contained in the fire mud. Pay attention to the rate at which the kiln temperature rises when drying the preheater. Generally, some small holes are left in the wall of the cyclone cylinder, so that the fire mud can be drained after being heated. If these small pores are not evaporated, the internal structure of the fire mud will be crushed and destroyed. Some expansion cotton is also placed between the fire mud, leaving room for expansion of the fire mud. After the preparation is completed, the burner is then inserted into the feed chamber so that the flame is in the center of the feed chamber. Because the diesel burner is inserted at one end, the flame is required.
Will be biased to one side, at this time should be careful not to let the flame touch the fire brick or fire mud, otherwise it will cause the heating speed to be too fast and destroy. Also pay attention to the temperature on both sides of the feed chamber.
Relatively close, not too high on one side, generally can be achieved by adjusting the position of the burner
4. Temperature control
When drying the preheater, drill holes in the iron plate of the preheater cyclone. The depth of the hole is at the junction of the root of the heat preservation brick and the fire brick. Generally, these holes are only used for drying the preheater. The position of the thermometer should not be too low, otherwise it will cause the pedestrian to touch and break, and it is also convenient to pick and place. Insert a mercury thermometer (aperture 3/8′′, temperature range from 0-350) for temperature measurement. The kiln decomposition kiln is usually equipped with 21 ignition drying starts, measuring the temperature every three hours, and then every six hours. After measuring the temperature of the burner, the flame remains stable and the combustion is complete. Generally, the fuel injection amount can be increased after the temperature in the feed chamber is stable. The temperature rise rate is 12 per feed chamber (first measurement point). The temperature of each of the other measuring points is gradually higher than 100 degrees when the hour rises by 20-30 degrees. However, after the temperature of the feeding chamber is higher than 350 degrees, the preheating machine can no longer increase the diesel supply.


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