Low-pressure steam ignition for converter furnaces
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During the initial operation of our unit, since medium-pressure steam was not available, low-pressure steam at 1.0 MPa was used; the oxygen pressure was kept at 1.0 MPa, the pressure in the coke oven was controlled at 0.5 MPa with a flow rate of 9,000 NM3/h. The exit temperature of the preheater was maintained at 695 degrees, while the temperature at the first point of the conversion furnace was 610 degrees, and ignition was successful. After temporary parking in January 2009, when restarting the operation, the low-pressure steam pressure could not be increased to 0.65 MPa due to issues with the power plant; I kept the oxygen pressure at 1.0 MPa, the pressure in the coke oven at 0.35 MPa with a flow rate of 9,000 NM3/h. The exit temperature of the preheater was maintained at 695 degrees, and the temperature at the first point of the conversion furnace was 598 degrees – ignition was successful.
The steam pressure is insufficient, and the pressure principle cannot be ensured (steam > oxygen > coke oven gas); it is very dangerous when pressure builds up in the system. When ignition occurs, the system pressure is too low, which can cause the airflow velocity to be too high; this leads to overheating of the catalyst layer as a result of combustion within it.
The temperature of low-pressure steam is relatively low, so the heating process may be slow. Moreover, it is very dangerous when the steam pressure is not higher than, or even lower than, the oxygen pressure; if pressure fluctuations occur in the system after oxygen is introduced and this leads to backflow of coke oven gas, the oxygen pipes could explode.