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In the sweltering summer heat, the residential buildings on the edge of the industrial zone always keep their doors and windows tightly shut at dusk-the roar of cooling towers and the low groans of exhaust fans weave an invisible sound barrier, shutting out the everyday life of the city. These "steel lungs" that support the lifeblood of modern industry, while exhaling heat, also imprint sound waves on the fabric of the city. How can we prevent the breathing of industry from becoming noise in our lives? A technological revolution focused on quiet is quietly taking place.
Core domain applications
As core components of industrial infrastructure, both are widely used in high-energy-consuming scenarios:
Cooling tower:
✅ Thermal power plant (steam turbine circulating water cooling)
✅ Petrochemical plant (reaction tower cooling system)
✅ Data Center (Server Cluster Cooling)
✅ Central air conditioning (cooling source for commercial complexes)
Exhaust fan:
✅ Boiler system (combustion air supply and flue gas emission)
✅ Industrial kilns (high-temperature gas conveying)
✅ Ventilation engineering (air exchange in tunnels/underground spaces)
✅ Dust removal equipment (negative pressure dust collection)
In-depth analysis of noise characteristics
Equipment | Dominant Noise Source | Spectral Characteristics | Sound Pressure Level Range | Propagation Characteristics |
Cooling tower | Water spray noise (60%) | Prominent mid-to-high frequency noise (1kHz-4kHz) | 7595dB(A) | Omnidirectional diffusion, strong penetration |
Fan aerodynamic noise | Significant low-frequency noise (63250Hz) | Prone to structural resonance |
Exhaust fan | Blade passing frequency noise | Discrete peak value (fundamental frequency + harmonics) | 85-110 dB(A) | Propagation over long distances along the duct |
Eddy current noise (wideband) | Mid-to-high frequency continuous distribution | Secondary radiation from shell vibration |
Typical case: The noise level of the cooling tower group in a chemical plant reached 93dB(A), with a peak value of over 100dB at 500Hz; the sound pressure level of the induced draft fan reached 108dB at the blade frequency of 250Hz, which triggered complaints from residents 100 meters away.
Multi-level noise control technology system
I. Targeted Noise Reduction Solution for Cooling Towers
1. Source control
Silencing type air duct: lined with micro-perforated aluminum plate (noise reduction ≥15dB)
Variable frequency water droplet noise reduction technology: Changes free-falling water to thin-film flow (water spray noise 12dB lower).
2. Blocking the transmission route
Three-dimensional sound absorption and insulation barrier:
Outer layer: 0.8mm galvanized steel sheet (sound insulation 30dB)
Middle layer: 50kg/m³ centrifugal glass wool (sound absorption coefficient 0.95)
Inner layer: Perforated fluorocarbon aluminum plate (corrosion resistant)
Defogging and noise reduction module: Water collector + acoustic louver combination (noise reduction 10dB/defogging rate 90%)
3. Intelligent Operation and Maintenance
Deploy an AI-powered voiceprint monitoring system to identify abnormal vibrations in wind turbine bearings in real time (early warning accuracy > 90%).
II. Comprehensive Noise Control of Exhaust Fans
A [Noise Source] > B (Silencer)
A > C (Soundproof enclosure)
A > D (Vibration-damping base)
B > E [Exit silencer: Reactive + Resistive composite structure]
C > F [Modular assembly enclosure: Insertion loss ≥ 25dB]
D > G [Spring damper: Vibration transmissibility < 5%]
Key technical parameters:
Muffler:
The resistance level is targeted at the leaf frequency (ΔL=20dB/250Hz).
Resistive section handles wideband noise (ΔL=15dB/1k4kHz)
Soundproof enclosure:
It adopts double-layer 12mm damping steel plate + 32mm rock wool (STC=42).
Vibration damping system:
Natural frequency ≤ 5Hz, avoid coupling with equipment excitation frequency.
Breakthrough in cutting-edge technology
1. Bionic noise-reducing blades:
Wind turbine blades with an owl-wing serrated structure (wideband noise ↓8dB)
2. Active noise reduction using phased array:
A loudspeaker array is arranged around the tower to emit anti-phase sound waves in real time (effective frequency band: 100800Hz).
3. Applications of acoustic metamaterials:
Local resonant units are embedded in the sound barrier (sound insulation is increased by 400% at 200Hz).
Policy and standards driven
Mandatory standard: GB 3096-2008 stipulates a daytime noise limit of 65 dB(A) for industrial areas.
Technical guidelines: The "HJ 2034-2013 Technical Specification for Environmental Noise Engineering" requires:
When the cooling tower is 30 meters from the factory boundary, the noise level is ≤60 dB(A).
Economic leverage:
In some regions, noise pollution discharge fees are levied on enterprises that exceed emission standards (3.2 yuan per decibel per month exceeding the standard).
Industrial noise control has transformed from a cost center into a value-creating process. With the deep integration of acoustic material innovation and intelligent control technology, future factories will achieve the synergistic evolution of "capacity improvement" and "acoustic environment optimization," injecting a quiet gene into industrial civilization.