- Priming ignition
Firstly, limestone or lime is paved on the discharging device at the kiln bottom until it is near the water level of the ignition hole as a protective layer. The thickness of the bottom material can be 1 ~ 3M. Add 800 ~ 1000kg firewood above the protective layer, including half of soft firewood and half of hard firewood. Put a small amount of hard firewood below, then put all soft firewood and shavings, pour a small amount of waste diesel oil, throw the ignited torch from the kiln or from the ignition hole, and then put the remaining hard firewood after observing that the fire has been ignited for a period of time.
- Temperature controlled drying kiln
After the priming ignition is completed, 600 ~ 500kg of hard firewood and 1000kg of coal (3 ~ 5cm) can be added every 30 ~ 60min according to the combustion condition; The material layer shall be thin and uniform, and the flame shall be seen when red. The heating rate shall be controlled by controlling the air volume entering the kiln according to the kiln drying curve. Stop adding coal 1 ~ 2 days before the end of the drying kiln, and maintain the drying kiln temperature with the remaining residual coal. After the completion of kiln drying, the bottom stone and ash shall be discharged and repaired after natural cooling.
Ignition and start-up process of gas fired shaft kiln
For the ignition and start-up of gas fuel shaft kiln, the operation rules for ignition and start-up shall be formulated according to the specific structure and conditions. The basic operation process is as follows:
- Check the negative pressure in the kiln: before starting the smoke exhauster before firing, after a certain time of draught, adjust the micro negative pressure in the kiln before firing.
- Blowdown of pipeline system: the gas pipeline system and burner shall be flushed and blowdown before ignition until the content of discharged gas is less than 1%, so as to prevent tempering during ignition. Open fire shall be prohibited in the process of blowdown. The cleaned blowdown gas shall be put into the atmosphere from the kiln top, and shall not be retained in the kiln. Check the gas pressure after blowdown to ensure the requirements of ignition and roasting process.
- Burner ignition: start the fan supplying air to the burner, supply the basic air volume, send the ignited igniter to the burner nozzle, gradually send the gas for ignition under the required negative pressure in the kiln, and gradually increase the amount of gas and air according to the combustion condition after ignition.
- Fire regulation: during ignition regulation, the composition of waste gas at the kiln top shall be continuously analyzed, and the amount of air blown in shall be increased or reduced.
- Feeding and trial firing: when the temperature of waste gas at the kiln top reaches 200 ℃, the feeding can be carried out, and the feeding speed shall maintain the temperature of waste gas at the kiln top not lower than 15 ℃. Generally, qualified lime can be burned 16 ~ 30h after ignition. At this time, the gas and air volume can be added to the rated value, and the shaft kiln can be turned into normal production.