CASE20 · Manufacturing · Steel melting and auxiliaries
Coordinating preheating, cycle duration and throughput in steel melting
Charge-level electricity is matched with operating logs to evaluate preheating, melting, waiting and tapping. A first-stage operating target is defined without mixing raw and filtered observation averages.
01 · CASE ANALYSIS
Operating challenge
Furnace control data and charge logs were separate. They needed to be aligned to analyze the combined influence of preheating, cycle time and output on electricity intensity.
Preheater use varied from zero to two activations per charge. Average total cycle duration was about 150 minutes; lower charge and daily throughput tended to coincide with worse intensity.
02 · CASE ANALYSIS
Data and operating relationships
Charge electricity, product/output, preheating count, melting/waiting/tapping durations, daily output, pump status and dust-collection pressure were reviewed together.
The raw charge average was approximately 559 kWh/ton. After excluding abnormal intensity periods, the detailed operating analysis averaged approximately 535 kWh/ton. The project’s final first-stage target separately uses 557 to 530 kWh/ton.
| Reference | Value | Meaning |
|---|---|---|
| All-charge observation mean | 559 kWh/ton | Raw observed population |
| Filtered operating-analysis mean | 535 kWh/ton | Abnormal periods removed |
| First-stage project target | 557 → 530 kWh/ton | Approximately 5% operating target |
03 · CASE ANALYSIS
Proposed operating changes
The report identifies favorable intensity where daily preheated charge count is about 25 or more and proposes preheating utilization around a 3-tonne-per-charge reference.
Reduce total cycle duration toward 110 minutes, with melting about 60–70 minutes and waiting/tapping about 30–40 minutes. Maintain output targets of at least 10 tonnes/charge and 300 tonnes/day, while protecting quality and process stability. Cooling-water VFD operation and dust-collection pressure require further review.
04 · CASE ANALYSIS
Target and verification
The approximately 5% is an operating target, not a confirmed saving. The dust collector’s reported differential pressure of about 241 mmAq exceeded the report’s 100–150 mmAq reference, supporting further diagnosis rather than a predefined savings claim.
M&V should account for production, product, melting temperature, residual metal and operator/equipment conditions. Keep raw observations, filtered data and contractual/project targets distinct.
| Indicator | Current condition | Target / review |
|---|---|---|
| Cycle duration | 150 min: melting 81; waiting/tapping 69 | 110 min: melting 60–70; waiting/tapping 30–40 |
| Output | Approximately 9–11 tonnes/charge | At least 10 tonnes/charge and 300 tonnes/day |
| Preheating | 0–2 activations/charge | Improve utilization; source reference approximately 3 tonnes/charge |
| Dust collector ΔP | 241 mmAq | Further diagnosis against report reference 100–150 mmAq |
05 · CASE ANALYSIS
Engineering lesson
Shorter non-production time and higher throughput can both lower kWh/ton. Analyze their combined effect instead of attributing all intensity changes to the furnace hardware.
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