36% Energy Saving and 10-Month Payback at a Home-Appliance Plant in Guangdong

A major home-appliance manufacturer in Guangdong runs multiple shifts with continuous, high-load compressed-air demand. Air was supplied from two stations, both using ageing fixed-speed compressors:

• Station 1: three 37 kW units and one 30 kW unit.
• Station 2: two 37 kW units and one 45 kW unit.

The machines were inefficient and spent a large share of time unloaded, wasting electricity. With round-the-clock operation, the annual electricity cost of compressed air remained high, and the waste was obvious. Compressed air is often one of the largest single electricity consumers in a factory, so the plant made it a priority for energy reduction.

The upgrade addressed both the equipment and the system:

• Compressor replacement: the high-consumption fixed-speed units were replaced with SIND DUALLUBE-VPM series two-stage, permanent-magnet variable-speed screw compressors. Two-stage compression lowers specific power, and variable speed eliminates most unload running.
• Pipework optimisation: the distribution layout was improved to reduce pressure losses between the stations and the points of use.
• Centralised intelligent control: a central controller adjusts load automatically and supplies air on demand across both stations.

Improving the efficiency of the core equipment and the match between supply and demand together unlocked the plant’s savings potential.

• More than 36% overall energy saving for compressed air.
• 10-month payback. The initial estimate was 15 months, but longer actual production hours and higher daily air consumption than expected increased the savings.
• Total investment recovered within one year.
• Automatic, demand-based supply across both stations.

For plants with multi-shift, high-load demand, two-stage variable-speed compressors under central control can pay for themselves within a year.