I. Characteristics of Stenter Exhaust
The stenter is one of the highest single-equipment energy consumers in printing and dyeing plants. Exhaust temperature often reaches 160~220°C, but accompanied by oil mist, fibers, and dye volatiles; entering the heat exchanger directly will rapidly foul and clog. So the first checkpoint of recovery is not heat exchange but purification.
II. Three-Stage Cascade Recovery
| Step | Function |
|---|---|
| 1. Oil mist filtration/electrostatic | Remove oil mist and fibers, protect the heat exchanger |
| 2. Air-to-air heat exchange | High-temperature exhaust preheats make-up air, saving heating |
| 3. Waste heat boiler/hot water | Medium-temperature section produces steam or hot water |
III. Benefit Estimation (Example)
- Exhaust: 18000 m³/h, 180°C → 120°C;
- Air mass flow ≈ 4.8 kg/s, recovered heat ≈ 4.8×1.0×(180−120) = 288 kW;
- Annual operation 7000 hours, standard coal saving ≈ 288×7000/(29307 kWh/tce×0.9) ≈ 76 tce;
- Carbon emission reduction ≈ 200 tons CO₂/year, with both economic benefit and compliance value.
IV. Engineering Red Lines
- No purification, no heat exchange: Putting a heat exchanger on without filtering will clog within three months;
- Anti low-temperature corrosion: Condensation of sulfur-containing flue gas produces acid; wall temperature must be above the acid dew point;
- Online ash cleaning: Reserve purge interfaces, turning shutdown cleaning into routine maintenance.