The technological calculation for synergistic system of BF slag waste heat recovery and carbon resources reduction

• A system was proposed to achieve the goal of energy saving and emission reduction.
• The BF slag waste heat and CO2-rich waste gas were converted and utilized.
• Technological calculation and exergy analysis were used to analyze in the system.
• About 120 m3 combustible gas was produced when using one ton BF slag to provide energy.

In order to achieve the conversion and utilization of BF slag waste heat and CO2-rich industrial waste gas, a synergistic system was proposed. The methods of technological calculation and exergy analysis were conducted to determine the performance of the gasifier in the system using the coal/waste gas gasification reaction to recover the BF slag waste heat. Above 85% BF slag waste heat was recovered, and the exergy efficiency reached 78.38% in molten and granules slag gasifiers, and about 80% CO2 was converted to syngas in the waste gas. In the coal/waste gas gasification process, the BF slag was used as heat carrier to guarantee the gasification reaction. The physical heat of the BF slag and chemical heat of coal were converted to the chemical and physical heat of syngas. The syngas physical heat was also recovered by heat exchanger to produce steam in the system. The waste heat of one ton BF slag at 1773 K was also calculated in the system consuming about 44.55 kg/tslag Datong coal, 146.12 m3/tslag industrial waste gas, and generated about 120 m3 syngas. In the whole system, the BF slag waste heat was converted and utilized, and the CO2-rich waste gas was recycled. The energy consumption and CO2 emission were decreased in iron and steel enterprise, so as to achieve the objective of energy saving and emission reduction.