Oven operation, precautions and safety precautions of silica fire brick for hot blast furnace

Operation of New Top-Fired Silica Brick Hot Air Furnace Oven

The 3# hot blast stove oven uses mixed gas as the combustion medium and compressed air as the combustion-supporting medium. It is planned to start the oven at 15:00 on November 21st in different heating stages according to the characteristics of the silica bricks.

1) Oven temperature control requirements

(1) The heating period of 20-200℃ is 5 days, the heating rate is 1.5℃/h; the constant temperature is 200℃ for 5 days.

(2) 200 ~ 300 ℃ temperature rise for 4 days, heating rate 1.0 ℃/h; 300 ℃ constant temperature for 5 days.

(3) The heating period of 300-600°C is 10 days, the heating rate is 1.25°C/h; the constant temperature is 600°C for 6 days.

(4) The heating period at 600-800°C is 4 days, the heating rate is 2°C/h; the constant temperature at 800°C is 2 days.

(5) The heating period of 800-1000°C is 1 day, and then the blast furnace gas is switched to the normal firing furnace, so that the hot blast furnace is further baked as a whole, and the temperature continues to rise evenly to reach the air temperature level required by the blast furnace.

(6) The whole oven process is carried out according to the oven curve. Adjust the gas volume carefully according to the change of the top temperature, and adjust it every 2 to 4 hours.

2) Oven temperature process control The actual oven time and temperature control are shown in Figure 1, and the actual oven time is 39 days. After the oven is completed, the oven manhole is closed, and the hot blast stove is subjected to a pressure test. After passing the test, the 3# hot blast stove is put into production. Figure 1 The plan and actual progress of the silica brick hot blast furnace oven

Silica brick hot blast furnace operation precautions

(1) In the oven, it is required to heat up according to the oven curve.

(2) The flue valve of the hot blast stove is in the open state before the ignition oven, and the other valves are in the closed state. During the drying period, a low negative pressure should be maintained in the hot blast furnace (the opening of the flue valve should be adjusted according to the flue gas temperature and top pulling force). In the initial stage of ignition, the ignition gun should be used to heat up. One flue valve can be completely closed and the other flue valve can be adjusted. valve opening.

(3) When the pressure of the gas pipe network is low, it is necessary to contact the dispatcher in time to ensure the gas supply and avoid stopping the hot blast stove in the middle.

(4) The oven operator should always observe the gas combustion of the oven burner. Due to the high moisture content of the refractory material in the initial stage of the oven, the flue has a small pulling force, which makes the flame combustion of the mixed gas burner extremely unstable and difficult to control, so it should be closely observed. Once the flame is turned off, turn off the mixed gas and compressed air immediately. After 5 to 10 minutes, check to confirm that the residual gas in the furnace has been drained, and then re-ignite.

(5) When adjusting the gas and air flow according to the oven curve, do not adjust continuously. The gas volume should be carefully adjusted according to the temperature indication on the arch side; when adjusting the gas volume, it should be stable and not too fast to avoid excessive temperature control changes. When the temperature of the arch side is low, increase the gas flow appropriately, and increase it several times, not at one time; when the temperature of the arch side is too high, reduce the gas flow appropriately, and do not reduce it too much. Properly adjust the air and gas ratio with each adjustment to ensure that the vault reaches the desired temperature.

(6) In the event of an electrical or mechanical accident that affects the oven, the gas, air and other valves on the oven burner should be quickly closed, and the oven should be continued after the accident is dealt with.

(7) If there is a problem with the oven temperature due to instrument measurement, repair it immediately. At this time, keep the oven gas volume and combustion-supporting air volume unchanged; after the instrument is repaired, if the temperature exceeds or is lower than the planned value, the temperature should be raised according to the oven curve. Adjust the speed; when the temperature is lower than the planned value, the oven time should be extended; if the temperature is higher than the planned value, keep a constant temperature, and continue to heat up after the time coincides with the established oven curve time.

(8) Adjust the opening of the flue valve according to the oven time and flue temperature. After the oven is finished, 100℃<exhaust gas temperature≤400℃.

(9) During the drying process, check the expansion of the newly renovated part of the hot blast stove body at any time, and make a mark.

(10) If there is a big abnormal situation in the oven, notify the relevant leaders in time, and do a good job of keeping warm.

(11) In blast furnace production, before the other 3 hot blast stoves are changed, the on-site oven personnel shall be notified in advance to observe the combustion of the burner of the 3# hot blast stove; the exhaust gas should be discharged slowly to avoid the backflow of the flue gas 3# hot blast stove affects the oven.

(12) When removing the blind plate of the 3# gas branch pipe, the blast furnace should be prepared in advance, and the gas should be purged after cutting the gas, and the gas and oxygen content of the gas pipeline should be tested. ~8h to complete).

Silica brick hot blast furnace operation safety precautions

(1) A comprehensive safety inspection shall be carried out before the oven, and all openings except for the oven manhole on the arch side must be effectively blocked.

(2) Before removing blind slabs and brick walls, a hazardous work safety permit shall be obtained.

(3) The newly connected gas pipeline is subjected to a pressure test before the gas is introduced to check whether there is leakage at the welding joint.

(4) Strictly follow the operating procedures when diverting gas, and do a burst test before ignition.

(5) In the event of fire extinguishing in the middle, the post should be confirmed according to the operation sequence when re-ignitioning. Single-person operation is prohibited in the gas area, and a gas alarm must be carried.

(6) When the 3# hot blast stove is turned into the blast furnace gas furnace, the gas protection measures should be taken when removing the blind plate of the combustion valve.