Stationary electric rotary screw compressor
A floor-mounted electric screw compressor feeding a workshop or plant ring main. Bought on efficiency and duty cycle, because the electricity bill exceeds the purchase price within a few years.
Features
- Specific power in kW per m³/min is the honest efficiency comparison; motor rating alone tells you nothing about air delivered.
- Fixed-speed machines are most efficient at full load, so they suit a steady demand with a receiver to absorb peaks.
- Variable-speed machines follow demand and avoid unloaded running, which pays back only where the load genuinely swings.
- Every 1 bar of unnecessary system pressure costs roughly 6 to 7 % more energy, so the set pressure is worth arguing about.
- Heat recovery from the cooling circuit can be used for space or process water heating, which changes the running-cost case materially.
- The machine needs a ventilated room with a stated air change rate; installing one in a cupboard de-rates it.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Free air delivery | 600 - 9 000 | l/min | Must exceed measured plant demand plus leakage. |
| Working pressure | 7.5 - 13 | bar | Every unnecessary bar costs energy permanently. |
| Motor rating | 7.5 - 90 | kW | Sizes the electrical supply and starter. |
| Specific power | 5.5 - 7.5 | kW per m³/min | The single best efficiency comparison. |
| Cooling method | air / water | Decides room ventilation or a water circuit. | |
| Recoverable heat | 6 - 75 | kW | Can offset a heating load entirely. |