NOISE MONITORING
REDUCING THE IMPACT: SILENCING
COGENERATION NOISE
As the number of Combined Heat and Power (CHP) installations continues to grow worldwide, Lee Nicholson, Managing Director of Wakefield Acoustics,
explains how early detection and preventative measures can mitigate the health and environmental impacts of noise in such applications.
Driven by the need to both conserve energy and guarantee grid reliability, the adoption and installation of Combined Heat and Power (CHP) systems has significantly gained traction over recent years with projections of continued growth. Amenities such as hospitals, hotels, factories, office buildings and even some residential apartments are adopting cogeneration as they look to conserve energy and guarantee energy supply reliability.
However, with an increasing number of CHP installations being installed on-site to provide power directly at point of use, excessive noise has quickly become a prominent issue which businesses are keen to address. Noise at Work and environmental noise legislation, an increasing public intolerance to noise, as well as the documented detrimental health impacts of excessive exposure to noise have only intensified the focus on reducing noise pollution in CHP installations.
DECREASING
COGENERATION NOISE All CHP systems have a prime mover/ electrical generator which emits ambient noise into the adjacent area and exhaust noise from the exhaust stream. Most CHP systems also have auxiliary equipment which can generate noise either continually or intermittently. Both intermittent noise and noise sources that emit discrete tones can cause a nuisance.
CHP installations usually operate continuously, but care must also be taken to shield sources of intermittent noise such as safety vents, pumps and compressors. Typical noise levels from
www.tomorrowshs.com
such plant is usually well in excess of the 85dB(A) daily exposure limit specified in The Control of Noise at Work Regulations 2005, and will likely lead to environmental noise complaints.
”WITH AN INCREASING NUMBER OF CHP INSTALLATIONS
EXCESSIVE NOISE HAS QUICKLY BECOME A PROMINENT ISSUE
BUSINESSES ARE KEEN TO ADDRESS.”
Designing a CHP installation often involves investigating the effects of the plant on the existing local noise profile. Both exhaust noise and ambient noise from the prime mover must be taken into consideration. For exhaust noise, engines and gas turbines frequently require a silencer in the ductwork or chimney to meet local environmental requirements. Exhaust silencer design for prime mover exhausts must consider the sound level characteristics as noise emissions are typically higher at low frequency. Silencers should be installed that are designed to give consideration to the system requirements without creating an excessive pressure drop across the silencer, as this can affect the prime mover’s performance and efficiency.
An acoustic enclosure is installed around the CHP prime mover/ electrical generator to reduce ambient noise levels, and in some cases the whole plant is installed in an acoustic housing that has been
specifically designed to attenuate noise. Taking into account specific site requirements, acoustic enclosures designs should take into consideration the inherent noise of equipment, and also the logistical and spatial limitations in terms of access to, from and around the power plant. Also key to the installation of enclosures, is the requirement for regular maintenance. With this in mind, acoustic enclosures are manufactured with numerous access doors and implement a fully demountable design. In line with the noise specification, enclosures also incorporate a fan assisted ventilation system to provide cooling airflow and prevent overheating.
For smaller CHP installations, a range of bespoke, and standard acoustic enclosures can be designed and manufactured to be skid mounted. These enclosures reduce the ambient noise emissions from CHP units to 70dB(A) and 65 dB(A) typically, but can be adapted to suit the requirements of the most onerous of noise specification requirements.
Whether installed in a commercial setting, public building, industrial site, or as part of a district heating system, left untreated, CHP systems can emit high levels of noise which can lead to environmental noise complaints. Increasingly stringent noise at work and environmental noise legislation, paired with a public less willing to accept environmental noise nuisance, as well as the documented harmful effects of noise pollution, mean the cost-effective implementation of noise control solutions is critical to all new cogeneration installations.
www.wakefieldacoustics.co.uk 31
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50