Fundamentals of noise control in Power Generation plant
The science behind the sound mitigation solution applied to power plants.
Soundproofing refers to the processes involved in checking the sound from entering or leaving a specified area by absorbing and/ or mitigating the sound. Soundproofing mechanisms can be employed in several situations, especially industries notorious for sound pollution mostly attributed to the use of heavy-duty machinery, Power Generation plants are part of these.
Noise pollution source in power generation plants
There are numerous main sources of noise within a power plant and only a few of the major causes are taken in the exam here.
The sound power level from equipment can spread from about 120 dB to over 155 dB depending on the size and type of machine. There is no easy method to generally categorize one unit as being noisier than another, in fact, the amount of MWs turbine produce does not directly affect the noise they produce. However, diesel engines are more predictable, and generally, the higher the horsepower or kilowatt rating, the higher the noise level because more cylinders and fuel are needed.
Here is a list of some of the common noise source in power plants:
- Combustion turbine (CT)
- Heat recovery steam generator
- Diesel engine
- Superchargers on diesel engines
- Steam generators, regulators, by-pass and control valves and piping
- Air-cooled condensers (ACC)
- Cooling towers, produce fan and gearbox noises
- Fuel gas pressure regulating, metering and valve stations
- Main step-up transformers
- Condensate pumps, condenser units, and associated piping
- Piping and pipe hangers not acoustically isolated from structures
- Blow-off and venting processes
- Remote water-pumping stations.
The sound emissions from power generation equipment can be reduced by applying noise control devices.
Sound Field Definition
To analyze noise from equipment, we need to define the sound field – that is, how the sound will propagate from the equipment or the sources of noise. Near field, far field, free field, and reverberant field are frequently mentioned. These are regions that describe certain characteristics of sound propagation as illustrated in the Figure.
Descriptions according to ISO 12001:2009
- Near field
- The near field of a source is the region close to a source where the sound pressure and acoustic particle velocity are not in phase.
- Far field
- The far field of a source begins where the near field ends and extends to infinity. Note that the transition from near to far field is gradual in the transition region. In the far field, the direct field radiated by most machinery sources will decay at the rate of about 6 dB each time the distance from the source is doubled.
- Free field
- The free field is a region in space where sound may propagate free from any form of obstruction.
- Reverberant field
- The reverberant field of a source is defined as that part of the sound field radiated by a source that has experienced at least one reflection from a boundary of the room or enclosure containing the source.
Fundamentals of Noise Control
Noise control or mitigation involves several steps, and the amount of noise reduction is driven by having to meet an environmental noise limit or some regulatory limit, not to mention workers’ safety. A simple model using the classical approach to noise control (shown below) allows the examination of the options for effective and economical noise control:
source of noise → path of noise →received noise
Applying noise control involves affecting one of these three elements. Most often it is the ‘path of noise’ that is controlled by the use of acoustic enclosures, barrier walls, silencers, and other similar noise control treatments. This method is the most widely used as the degree of noise control can be tailored depending upon the noise requirements and generally it is the more economical approach. The control on the ‘source of noise’ can be expensive because it may require a complete redesign and retooling process which takes time and money.
For new plants, examine the structure arrangement and locate the noisiest equipment or operations away from noise-sensitive areas. Grouping smaller sources together can be beneficial in that a common noise barrier or enclosure can solve a lot of small problems.
Stopson Italiana Soundproofing Solutions
Enclosures and Barriers
Shaped around noisy equipment, indoor or outdoor, on-base or off-base, designed to provide optimum noise attenuation in any critical environment. Made of modular acoustic panels and linings for sound isolation while ensuring equipment maintenance, ventilation, weather protection, and fire safety.
- Noise abatement by 15dB(A) to 50dB(A)+
- Vibration absorbers, anti-shock systems with noise control settings
- Combustion air intake Unit with optional air filtration
- Exhaust gas removal for combustion engines
- Indoor/Outdoor Applications
Silencer and other solutions are available at Stopson Italiana, Check-out all the soundproofing products.