CASE22 · Manufacturing · Blast-furnace blowers
Diagnosing blast-furnace blower intensity, pressure and IGV operation
Seasonal blower data separate equipment differences from weather effects. Pressure margins, duct losses and unusual IGV readings are investigated while avoiding an unsupported filter-efficiency claim.
01 · CASE ANALYSIS
Operating challenge
Annual blower electricity cost was approximately KRW 145 billion. Seasonal airflow changed little, but summer power and intensity increased.
Some blowers showed very low or negative IGV readings despite high load, calling for field checks of signal consistency and control logic. Intake-filter differential pressure did not show a clear correlation with intensity.
02 · CASE ANALYSIS
Data and diagnostic indicators
The comparison used electricity/cost, power, normalized airflow, intensity, load, IGV opening, discharge/furnace-side pressures, duct losses, weather and intake-filter ΔP.
Overall intensity averaged approximately 0.078 kWh/Nm³; unit values ranged from about 0.075 to 0.081. Average power was 33.1 MW per furnace, about 34.8 MW in summer. Summer intensity was approximately 7.2% above winter.
| Indicator | Value |
|---|---|
| Overall / unit UPI | 0.078 / 0.075–0.081 kWh/Nm³ |
| Mean / summer power | 33.1 / 34.8 MW per furnace |
| Summer intensity increase | Approximately 7.2% over winter |
| Mean load / IGV | 91% / 20% |
| Mean / lowest duct loss | 0.13 / 0.09 kg/cm² |
03 · CASE ANALYSIS
Operating opportunities
Compare efficient blower conditions under the required blast flow and pressure. Review unnecessary pressure margins only while satisfying furnace operating and safety requirements.
The reported mean supply pressure was approximately 4.3 kg/cm², with some furnaces at 4.5 against a lower group around 4.0. Duct loss averaged 0.13 kg/cm² and reached about 0.09 in the lowest-loss furnace. Verify unusual IGV signals before changing control.
04 · CASE ANALYSIS
Evidence and M&V
The maximum approximately 8.2% unit-intensity spread is not a savings rate. The report does not provide confirmed post-improvement energy or cost savings.
Use production conditions, required blast flow/pressure, ambient temperature and blower combinations in the baseline. A lack of clear filter-ΔP correlation means filter work should not be assigned a quantified benefit without further evidence.
| Finding | Meaning |
|---|---|
| Unit intensity spread: approximately 8.2% | Benchmark opportunity; not verified saving |
| Supply pressure: 4.5 versus 4.0 kg/cm² groups | Approximately 11% reported difference; check required pressure |
| Low or negative IGV values | Check signals and actual controls |
| Filter ΔP versus intensity | No clear correlation established |
05 · CASE ANALYSIS
Engineering lesson
Diagnosis includes findings that do not support the initial hypothesis. Record the absence of clear filter correlation and prioritize the better-supported pressure, signal and operating-point investigations.
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