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During the summer heatwave, residential buildings on the edge of industrial zones often close their doors and windows in the evenings-the roar of cooling towers and the hum of induced draft fans weave an invisible sound network, isolating the hustle and bustle of the city. These "giant lungs of steel" that sustain the lifeblood of modern industry, while breathing in and out heat, also imprint sound waves on the urban fabric. How can we make the breathing of industry no longer become the noise of daily life? A technological revolution in silence is quietly taking place.
Core field applications
As core components of industrial infrastructure, they are widely used in high-energy consumption 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 (cold source for commercial complexes)
Induced draft fan:
✅ Boiler system (combustion air supply and flue gas emission)
✅ Industrial kilns (high temperature gas transportation)
✅ Ventilation engineering (tunnel/underground space ventilation)
✅ Dust removal equipment (dust negative pressure 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%) | Mid- and high-frequency prominence (1k4kHz) | 7595dB(A) | Omnidirectional diffusion, strong penetration |
Fan aerodynamic noise | Low frequency is significant (63-250Hz) | | Can easily induce structural resonance |
Induced draft fan | Blade pass frequency noise | Discrete peak (fundamental frequency + harmonics) | 85110dB(A) | Long-distance propagation along the duct |
Eddy current noise (broadband) | Medium and high frequency continuous distribution | | Secondary radiation from shell vibration |
> Typical case: The noise level of the cooling tower group of a chemical plant reached 93dB(A), with a peak exceeding 100dB at 500Hz; the sound pressure level of the induced draft fan at a blade frequency of 250Hz reached 108dB, triggering complaints from residents 100 meters away.
Multi-level noise control technology system
1. Targeted noise reduction solution for cooling water towers
1. Source Control
Silencer air duct: lined with micro-perforated aluminum plate (noise reduction ≥ 15dB)
Variable frequency water drop noise reduction technology: changes free falling water into thin film flow (sprinkling noise ↓12dB)
2. Blockage of transmission paths
Three-dimensional sound absorption and insulation barrier:
Outer layer: 0.8mm galvanized steel plate (sound insulation 30dB)
Middle layer: 50kg/m³ centrifugal glass wool (sound absorption coefficient 0.95)
Inner layer: Perforated fluorocarbon aluminum plate (anti-corrosion)
Mist and noise reduction module: water collector + acoustic shutter combination (noise reduction 10dB/mist elimination rate 90%)
3. Smart Operation and Maintenance
Deploy an AI voiceprint monitoring system to identify abnormal vibration of wind turbine bearings in real time (warning accuracy > 90%)
2. Comprehensive control of induced draft fan noise
A[noise source] > B(muffler)
A > C (soundproof enclosure)
A > D (vibration damping base)
B > E [Outlet muffler: resistive + resistive composite structure]
C > F[Modular assembly enclosure: insertion loss ≥ 25dB]
D > G[Spring damper: vibration transmission rate <5%]
Key technical parameters:
Muffler:
Resistance section for leaf frequency (ΔL=20dB/250Hz)
The resistive section handles broadband noise (ΔL=15dB/1k4kHz)
Acoustic enclosure:
Double-layer 12mm damping steel plate + 32mm rock wool (STC=42)
Vibration reduction system:
Natural frequency ≤ 5Hz, avoid coupling with the equipment excitation frequency
Cutting-edge technological breakthroughs
1. Bionic noise reduction blades:
Wind turbine blades based on the owl-wing sawtooth structure (broadband noise ↓8dB)
2. Phased Array Active Noise Cancellation:
A speaker array is arranged around the tower to emit reverse-phase sound waves in real time (effective frequency band: 100-800 Hz)
3. Application of acoustic metamaterials:
Local resonance units embedded in the sound barrier (200Hz sound insulation increased by 400%)
Policy and standards driven
Mandatory standards: GB 30962008 stipulates that the daytime noise limit in industrial areas is 65dB(A)
Technical Guidelines: "HJ 2034-2013 Environmental Noise Engineering Technical Specifications" requires:
When the cooling tower is 30 meters away from the factory boundary, the noise level is ≤60dB(A)
Economic leverage:
Some regions impose noise pollution fees on businesses that exceed the standard (3.2 yuan per decibel per month).
Industrial noise control has transformed from a cost center into a value-creating process. With the deep integration of innovative acoustic materials and intelligent control technologies, future factories will achieve the coordinated evolution of "capacity improvement" and "acoustic environment optimization," injecting tranquility into industrial civilization.