The traditional steel rolling process is that the steel slabs obtained by steelmaking are cooled by stacking, transported to a rolling mill, and then heated by a heating furnace to be rolled into steel. There are two defects in this process: 
1. After the steel billet is pulled out from the steelmaking continuous casting machine, it has a temperature of 700-900 °C on the cold bed , and the latent heat of the billet is not effectively utilized. 
2. After the steel billet is heated by the coal-fired heating furnace, the surface loss of the billet is about 2.5% due to oxidation loss .

In order to fully save energy , the continuous casting billet is subjected to on-line heating and uniform temperature heating by medium frequency induction heating. 
A, process parameter 1 , continuous casting blank size: 6000 (length) × 150 (width) × 150 (thickness) 2 , the line speed is up to 15m / min , the speed adjustment range is 9 ~ 15m / min , the speed of each billet is Constant. 3 , temperature distribution ( 1 ), continuous casting billet section temperature distribution characteristics, the internal temperature belongs to the high temperature region, the temperature is 1100 ° C ; the external is the low temperature zone, the temperature is 800 ° C , the low temperature zone is the part that needs to be increased by 300 ° C. ( 2 ) The temperature distribution characteristics of the head and tail of the continuous casting blank, usually the head temperature is lower than the tail temperature by about 50 °C . 4 , the user needs to ensure the squat: 30mm ; sickle bend: < 30mm

 B, scheme design: 1 , warming capacity: the entire billet is heated to 1100 ° C ; 
2 , the average temperature capacity: through the induction heating furnace , to ensure that the temperature uniformity of the billet is better than the natural state before heating; 
3 , the intermediate frequency power supply a ) according to the process index, from 800 ° C to 1100 in 1 minute °C , the required heating power is rounded to 5700KW ; b ) The theoretical calculation of the power consumption of the billet is 38 degrees (such as heating 200 degrees Celsius, the power consumption of the billet is 25 degrees); c ) to ensure the continuous operation of the furnace Reliability, we divide 5700KW intermediate frequency power supply into 2 sets of equipment, each set of 5700KW , 1 with 1 preparation; 4 , induction heating furnace: a ) According to the number of power supply settings, it is determined to use four induction heating furnaces (two and two) , both composed of a set by a medium frequency power supply; B ) placed in each of two . 3 only between the pinch rolls, roll spacing 2.6 meters towards the entrance to the casting direction need two sets of pinch rolls, roll spacing 1.6 meters, the roller diameter is about 200mm . The effective inductor is about 1 meter long and the total length of the sensor is 1.2 meters. c ) The inner space of the induction heating furnace : the billet is 150×150 billet, the inside of the inductor is also rounded square hole, the size is 280×280 , refractory The thickness is 20mm , and the net space around the slab and the refractory material is 45mm ; d ) The oxide rinsing ditch should be designed along the center line of the heating roller, the depth is larger than the cable ditch, and the unidirectional grading is carried out, and the roller is turned at the bottom to lead to the oxidation. Skin sedimentation pits, regular salvage. 5 , the speed of the billet in the medium speed transmission zone must meet the safe distance of 10 meters from the medium speed to the slow speed . It ensures that the speed of the billet has dropped to a slow and constant speed when it enters the induction furnace . 6 , using two-point temperature measurement: the entrance constant velocity section is 7 meters away from the entrance , set a thermometer, check the temperature of the billet, to determine the temperature distribution, and select the appropriate intermediate frequency voltage, the inlet uniform velocity section is 1 meter away from the entrance Position, set a trip switch to start the intermediate frequency power supply boost heating. A thermometer is placed at a distance of 1 m from the exit to display the heated temperature. 7 , temperature control mode: A) simple segment selection mode, the slab temperature to 700 deg.] C as a starting point by 50 deg.] C for stride segment, each segment corresponding to a different frequency voltage (by setting each field test segments corresponding to the intermediate frequency voltage); B) for example, if the slab temperature at 800-850 deg.] C a range, selected intermediate voltage 1600V ; corresponding to 850-900 deg.] C of the intermediate frequency voltage is 1500V , corresponding to 900-950 ℃ frequency voltage is 1400V , set in turn; c) According to the control method of ( 1 ), ( 2 ), the temperature of the billet at the outlet of the furnace is theoretically up to 50 °C , that is, the temperature range is 1050-1100 °C ; d) when the induction furnace is empty (without billet), the IF output voltage is automatically reduced to a minimum of approximately 200V for stable operation . 

C , investment costs

1，an equipment investment cost 450 million yuan

2 , construction investment cost 50 million yuan Total: 500 million yuan

D , energy efficiency analysis 1 , the original slab heating furnace process , the consumption of coal the amount of 80 kilogram / ton of steel (heat value of 6400 kcal / kg), equivalent to 72 kg of coal; technological process for the energy consumption per ton of steel after electricity consumption 38 is KW.T , equivalent to 13.3 KG coal; 2 , a steel rolling mill production is expected . 19 millions of tons The annual standard coal savings are: ( 72-13.3 ) ÷ 1000 × 190000 tons = 11153 tons of standard coal.