Building on an already successful relationship with China Steel, their parent company, Dragon Steel placed a contract with Primetals Technologies to design and supply a 2.5 Mtpa blast furnace for the first phase of their new integrated steelworks complex in Taichung, Taiwan.
Challenge
Prior to the start-up of the first phase, a second contract was placed to continue the ongoing development of the site with the addition of a second blast furnace to increase the total installed iron capacity to 5.0 Mtpa. Installation and commissioning of blast furnace No. 2 was required to proceed in parallel with the operation of blast furnace No. 1, but without impacting the production requirements.
Blast Furnace No. 1 and No. 2
Solution
The solution ensured efficient use of the available space while minimizing any additional engineering by substantially mirroring the phase 1 plant. The very good relationships built during phase 1 with the new plant operating and maintenance teams allowed the detailed planning and implementation of necessary utility tie-ins to progress without issues. This close cooperation with the client ensured major equipment could be made live and commissioned without any unscheduled impact on the functioning phase 1 production plants. The phase 2 plant incorporated extensions to the operating blower and PCI plants, which were undertaken using a modular format so that in future operations there would be full interchangeability between blast furnaces.
Scope of Supply
- As part of phase 1, Primetals Technologies delivered the basic and detailed engineering for blast furnace No. 1 plus all the equipment excluding civils and lagging. This included the blast furnace and cooling systems plus ancillary equipment, including 2 blowers, hot blast stoves, stockhouse, coal grinding and injection, casthouse, gas cleaning, gasholder, and top gas recovery turbine.
- As part of phase 2, a similar scope was supplied but with minimized engineering to incorporate the mirrored blast furnace No. 2. The majority of the ancillary plant was the same as phase 1, but the common areas of the blower house and coal grinding unit were extended to support the new capacity requirements.
- Both phases included construction and commissioning supervision.
- Performance guarantees for key production and operating parameters.
Blast furnace:
- Modern free-standing design with advanced instrumentation monitoring to enable high-performance operation
- Furnace profile, utilizing Primetals Technologies’ successful global experience with copper and cast iron staves, designed to meet the needs for a long campaign life
- Carbon hearth with deep sump and ceramic pad for long life
Blast system:
- Blower house incorporating 3 electrical axial blowers, each of 100% capacity for a single blast furnace and with interchangeability to provide a common standby
- 3 external combustion chamber stoves providing hot blast temperatures of 1,250 °C
- Waste heat recovery to enable efficient balancing of plant needs and to minimize fuel enrichment costs
Process gas system:
- Dustcatcher
- Triple-cone wet scrubber with inclined external demister to ensure the best conditioning of the process gas
- Top gas recovery turbine
- Gasholder
- PCI
- Common grinding system with 3 streams feeding 2 product silos for maximum availability
- Individual injection systems capable of up to 180 kg/tHM
Furnace charging:
- An in-line stockhouse capable of providing for a range of burden mixes with up to 30% pellets
- Single main charge belt conveyor feeding a parallel hopper top with 50% overcharge capacity
Casthouse:
- Flat-floor casthouse for optimum ease of operation
- 3 tapholes incorporating Primetals Technologies hydraulic taphole equipment
Blast Furnace No. 1 and No. 2
Results
Both furnaces continue to maintain performance over the longer term, with blast furnace No. 2 exceeding the design figure of 2.5 Mt of hot metal within the first year, just as blast furnace No. 1 exceeded 10 Mt within 4 years.
Both furnaces have reached production levels in excess of 8,200 tHM/d and continue to meet the key production and operating parameters.
Furnace Design Parameters
- Average production: 7,143 tons per day
- Peak production: 7,857 tons per day
- Furnace hearth diameter: 12.0 m
- Furnace working volume: 2,799 m³
- Furnace inner volume: 3,274 m³
- Top gas operating pressure: 2.50 bar g
- Blast pressure at furnace: 4.20 bar g
- Normal productivity on inner volume: 2.18 tHM/d/m³
- Normal productivity on hearth area: 63.2 tHM/d/m²
- Number of tuyeres: 32 off
- Number of tapholes: 3 off
Blast Furnace No. 1 and No. 2
Benefits
- High-efficiency stoves with waste heat recovery system
- High-rate coal injection system
- Furnace design for low maintenance cost with commonality of spares between furnaces
- Utilization of repeat engineering and key equipment supply
Conclusion
- Blast furnace No. 2 has exceeded the design figure of 2.5 Mt of hot metal within the first year.
- Blast furnace No. 1 has exceeded 10 Mt of hot metal within 4 years.
- Both furnaces have reached production levels in excess of 8,200 tHM/d and continue to meet the key production and operating parameters.
