Process reasoning
Power in kW is an instantaneous rate; energy in kWh is accumulated over time. A batch machine can have acceleration peaks and lower-power process stages. A continuous machine may run at several loads during a shift. Feed pumps, hydraulic units, polymer systems and conveyors can be outside a quoted drive figure. The chosen denominator matters: a dilute feed can look efficient per cubic metre while using more energy per tonne of recovered dry solids.
ILLUSTRATIVE EXAMPLE
Apply the reasoning
An illustrative package averages 45 kW during 8 operating hours and processes 6 tonnes of dry feed solids. Energy is 360 kWh and the normalized value is 60 kWh per tonne of dry feed solids. If only 95% of those solids are recovered, energy per tonne of recovered solids is approximately 63.2 kWh. State which denominator is used and include idle energy where relevant.
What to record
| Item | Basis to document |
|---|---|
| Nameplate power | Installed rating; not the operating average |
| Measured energy | Metered kWh over a stated interval |
| Boundary | Main drive, auxiliary drives, pumps and handling equipment |
| Normalization | Per m³ feed, tonne dry feed solids or tonne recovered product |
Review checklist
- Compare the same feed and product quality.
- Include start-up, idle and cleaning periods consistently.
- Record throughput and capture during the energy measurement.
- Separate measured data from a supplier estimate.
Your next decision
Request an energy balance tied to the proposed operating schedule. Avoid choosing solely on a smaller motor: the machine may operate longer, recover less product or shift energy demand downstream. Use energy as one component of total cost alongside chemicals, consumables, labour, transport and drying. Do not publish percentage savings without a documented baseline and test boundary.