Thermal system:
1.1.1 Rolling temperature:
990±20℃, the furnace temperature of each section is controlled in a balanced and stable manner, and the heating time is 90 minutes.
1.1.2 Furnace temperature control
Cold billet furnace temperature control（℃） | Hot billet furnace temperature control（℃） | ||||
soaking section | (II) heating | (I) heating | soaking section | (II) heating | (I) heating |
1090 | 1090 | 980 | 1090 | 1090 | 950 |
±20 | ±20 | ±20 | ±20 | ±20 | ±20 |
Note: The furnace pressure is controlled at (5-40)Pa, and the residual oxygen is controlled at (3-5)%.
1.1.3 The adjustment principle and method of furnace temperature when affected by abnormal factors:
1）When the gas pressure and calorific value fluctuate, the adjustment principle is that the furnace temperature, furnace pressure and residual oxygen content meet the requirements of 1.2, and the fuel combustion should be sufficient. The method is to adjust the opening of the gas and air control valves according to the furnace temperature and furnace pressure data displayed by the instrument, and to judge whether the fuel is completely burned by observing the color of the flame, and then adjust the air-fuel ratio.
2） When an accident occurs in the rolling line and emergency shutdown occurs, contact the main console in time to learn the rolling stop time, and implement the rolling stop cooling system according to the rolling stop time.
Stop rolling time | (I) heating | (II) heating | soaking section | Heating time before rolling start |
30 | — | -50 | -30 | Start heating 10 minutes before rolling |
30~60 | — | -100 | -50 | Start heating 20 minutes before rolling |
60~120 | flameout | -150 | -80 | Start heating 30 minutes before rolling |
120~180 | flameout | -250 | -100 | Start heating 50 minutes before rolling |
180~240 | flameout | -250 | -150 | Start heating 60 minutes before rolling |
Standard and requirements for quality inspection of billets before charging
1.2.1 Dimensions
1) The standard size of the continuous casting billet is 160*160*12000mm, the length of the four sides of the cross section is equal, the four corners are all 90 degrees, the bevel at the end is less than or equal to 12mm, and the belly is less than or equal to 4mm.
2) The curvature of the continuous casting billet shall not be greater than 20mm per meter, the total curvature shall not be greater than 2% of the total length, and there shall be no obvious torsion.
1.2.2 Weight
The theoretical weight of the continuous casting slab is 2334Kg, and the weight deviation shall not be greater than 3‰ of the theoretical weight.
1.2.3 Surface Quality
1) The surface of the continuous casting billet shall not have any visible reconnection, peeling, scarring or inclusions.
2) The continuous casting billet shall not have cracks with a depth greater than 1mm.
3) The continuous casting billet shall not have scratches, indentations, pores, wrinkles, cold splashes, pits, bumps, and transverse shock marks with a depth or height greater than 2mm.
4) The continuous casting billet shall not have shrinkage cavities, subcutaneous bubbles and cracks.
Operation requirements and precautions:
1.3.1 Strictly implement the gas safety operation rules.
1.3.2 Strictly implement the operation “three diligence” (diligence observation, diligent adjustment, diligent contact).
1.3.3 Strictly implement the heating temperature system and the rolling stop cooling system.
1.3.5 Reasonably control the air-fuel ratio according to the gas pressure to ensure complete combustion of the gas.
1.3.6 Keep a slight positive pressure to burn the steel, and the furnace pressure is controlled between 0 and 40Pa.
1.3.7 In order to ensure the safety of the equipment, the inlet temperature of all cooling water in the heating furnace is less than 32℃, the outlet temperature is not greater than 45℃, and the pressure is ≥0.3Mpa.
1.3.8 The air and gas preheating temperature can reach about 1,000 degrees, the air and gas pressure in front of the furnace is ≥3.5KPa, and the flue gas discharge temperature is <200℃.
