Electro- or Turbo-Driven?—Analysis of Different Blast Processes of Blast Furnace
2.1. Description of Electro- and Turbo-Driven Blast Process
2.2. Turbo-Driven Blast Processes Survey
- SISCO: The company used both of the two driving modes; the turbo-driven mode was used for the blasting of large BFs with the volume of 2700 m3 and 3200 m3, and the electro-driven mode was used for the blasting of small BFs with the volume of 420 m3, 450 m3, and 750 m3. When designing large BFs, considering the insufficient electricity supplied by SISCO itself and the stability of the steam pipe network, SISCO originally adopted the turbo-driven mode. After years of operating practice, the company observed that the turbo-driven blast process has many auxiliary processes and a high failure rate, which are reflected in high energy consumption and high costs of turbo-driven blast. Therefore, in addition to improving the stability of the power grid, the company plans to convert the turbo-driven blast process of its BFs into the electro-driven one.
- XBISCO: The turbo-driven blast process was mainly used for BF blowers, air compressors in the oxygen-making plant and sintering drawing fans, while the electro-driven blast process is employed in all other cases. Among them, the steam generated by four 180 t/h boilers constituted the power source of four 40 MW BF blowers and two 10 MW sintering drawing fans; the steam generated by two 130 t/h boilers and one 220 t/h supplied two 20 MW air compressors in the oxygen plant. XBISCO believes that the turbo-driven blast process has low direct investment costs. For the entire company, if CCPP projects are not considered, the boilers will be indispensable, and adopting the turbo-driven blast process can save the cost of one generator set. In fact, the adoption of an electro-driven blast process to increase the plant capacity would require an additional substation, leading to an extremely high fixed cost. Moreover, it is worth noting that a turbo-driven blast process is very reliable if properly maintained. XBISCO plans to continue the adoption of the turbo-driven mode for its newly built Corex utility energy area, in which two 240 t/h boilers drive two 20 MW air compressors in the oxygen plant.
- Xuanhua Steel: The company adopted the turbo-driven blast process on its four BFs in service (two 2500 m3 BFs, one 2000 m3 and one 1800 m3). Xuanhua Steel has two thermal workshops; the first workshop has two 160 t/h and a 180 t/h boilers that supply two 2500 m3 BF blowers; the second workshop has three 75 t/h, two 130 t/h and one 180 t/h boilers that supply a 2000 m3 BF and an 1800 m3 BF blower. Moreover, Xuanhua Steel also applied the turbo-driven blast technology to drive pumps and fans.
- Ansteel: The company has currently eight BFs and ten blowers. Among them, there are three electro-driven blowers for three 3200 m3 BFs, and five 2580 m3 BFs for seven turbo-driven blowers (plus two as backup). At present, three turbo-driven blowers are too old and need to be revamped and converted. According to conducted technical and economic analysis, Ansteel considered the electro-driven blast technology the most cost-effective solution, and converted the old three turbo-driven blowers into two new 6500 m3/min electro-driven blowers.
3. Analysis of Energy Efficiency of Blast Process
3.1. Theoretical Minimum Specific Steam Consumption of Blast Process
3.2. Energy Efficiency of Blast System
4. Analysis of Energy Consumption per Ton of Steel
4.1. Calculation Method of Energy Consumption
- x—Standard coal coefficient of steam, kgCE/kg;
- 0.34 × 10−4—Unit conversion coefficient of kJ and kgCE;
- R—Gas constant;
- H—Specific enthalpy of steam at temperature T and pressure p;
- s—Specific entropy of steam at temperature T and pressure p;
- h0—Specific enthalpy of steam at environmental temperature T0 and environmental pressure p0;
- s0—Specific entropy of steam at environmental temperature T0 and environmental pressure p0.
4.2. Influence of Driving Mode on Energy Consumption per Ton of Steel
- m—consumed steam by turbo-driven blast;
- n—consumed steam by electro-driven blast;
- xs—standard coal coefficient of steam;
- xe—standard coal coefficient of electricity;
- pHM—iron-to-steel ratio;
- ηe—generating efficiency of steam.
5. Analysis of Energy Cost
5.1. Energy Cost of Blast Process
5.2. Influence of Driving Mode on Total Energy Cost per Ton of Steel
6. Case Study
6.1. Case 1: Company A
6.2. Case 2: Company B
7. Conclusions and Recommendations
Conflicts of Interest
|CCPP||combined cycle of power plant|
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|Steam||Temperature (°C)||Pressure (MPa)|
|Electro-driven||Upper-limit efficiency (%)||99.5||37.90||98.5||94||98||99||97||95||99||30.90|
|Lower-limit efficiency (%)||98.5||35.34||98.0||92||98||98||97||85||97||24.11|
|Turbo-driven||Upper-limit efficiency (%)||99.0||37.03||−||−||−||−||−||−||100||36.66|
|Lower-limit efficiency (%)||97.0||30.70||−||−||−||−||−||−||100||29.78|
|BF||Productivity||Blast Flow Rate||Steam Consumption|
|Productivity||Blast Flow Rate||Steam Consumption|
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Sun, W.; Zhao, Y.; Wang, Y. Electro- or Turbo-Driven?—Analysis of Different Blast Processes of Blast Furnace. Processes 2016, 4, 28. https://doi.org/10.3390/pr4030028
Sun W, Zhao Y, Wang Y. Electro- or Turbo-Driven?—Analysis of Different Blast Processes of Blast Furnace. Processes. 2016; 4(3):28. https://doi.org/10.3390/pr4030028Chicago/Turabian Style
Sun, Wenqiang, Yueqiang Zhao, and Yunchun Wang. 2016. "Electro- or Turbo-Driven?—Analysis of Different Blast Processes of Blast Furnace" Processes 4, no. 3: 28. https://doi.org/10.3390/pr4030028