NOISE CONTROL FOR CHP John Hargreaves, technical sales manager at Wakefield Acoustics explains that although combined heat and power (CHP) systems provide a host of benefits, they can also produce high noise emissions, and organisations wishing to install them must also consider noise control in order to comply with strict regulations

passing through the ventilation system, acoustic louvres or attenuators are likely needed to be installed. To provide maintenance access,

enclosures can be fitted with integrated lifting beams, doors and removable walls, while specialised finishes and materials are used to defend them from weathering and corrosion.

CHP NOISE CONTROL IN PRACTICE Wakefield Acoustics was commissioned to provide the noise control solutions for two 1500kW gas engines at a major residential and commercial complex in London. To minimise disruption, prevent loss of


he obvious advantages of onsite generation have led to rapid growth in

the adoption of cogeneration systems across the UK. The results of a recent study by Centrica1

found 26 per cent of

the 1,000 organisations surveyed were already using CHP and/or solar power systems, with a further 33 per cent actively considering installation. While CHP systems deliver benefits

such as energy efficiency, lower costs and reduced emissions, the gas engines can emit noise levels of 110dB(A). This figure significantly exceeds the maximum exposure allowed under the UK’s Control of Noise at Work Regulations 2005, currently 85dB(A) for eight hours in any 24-hour period. Indeed, where acoustically reflective surfaces, like concrete, surround the CHP plant, this can easily rise above 120dB(A), restricting employee exposure to less than one minute in any 24-hour period. The requirement for any organisation

wishing to install a CHP system, as well as the equipment supplier, is to factor in effective noise reduction solutions from the outset in order to ensure compliance with noise regulations, and to protect those who come into proximity with the system. Today’s noise control technology for

on-site generation schemes has evolved to meet these regulations and safety concerns. However, as every plant


installation is unique, there is no one-size-fits-all solution. When specifying the right noise control products and installation methods for CHP, detailed consideration of the specific system’s function, location and permitted noise levels, as well as other pertinent factors, is required. An additional consideration to the risk to

operatives’ health from exposure to breakout noise are the stringent limits dictated by local authorities to lower noise emissions which could affect nearby noise sensitive properties. Full acoustic enclosures are a necessity

for reducing breakout noise emissions to levels below those demanded by the Control of Noise at Work Regulations, and in compliance with planning authorities. The high performance, composite acoustic panelling used to build full enclosures enables CHP systems to operate 24/7 in the vicinity of occupied buildings, making them suitable for industrial, commercial and residential areas. The noise levels achieved make facilities safe for workers and others, though ear protection would still need to be worn inside the enclosure when the plant is operational. Alongside a full enclosure, there are

other challenges to consider, including the installation of an engine exhaust silencer capable of withstanding the gas flow rate, pressure and temperature. Additionally, to reduce excessive noise

amenity and to guarantee the safety of CHP plant operators, a full ventilation system was supplied and installed for the concrete engine cells, together with purposely designed attenuator units and acoustic louvres to ensure compliance with acoustic criteria set by the local authority. The high airflow needed to cool the

engines required large ventilation attenuators. Due to limited installation space and to minimise disruption, these were manufactured flat-packed and erected on-site. To reduce noise breaking out into the

duct and bypassing the ventilation attenuators, the engine cells’ ductwork sections were acoustically lined. Ventilation fans, filter boxes and dampers were also fitted, together with a steel support structure designed to carry the weight of the large engine silencers. To enable maintenance, load-tested lifting beams were installed along with an access gantry. Wakefield Acoustics was able to meet

planners’ strict targets, reducing the source noise levels of almost 100dB(A) per engine cell to 60dB(A) at 1m from inlet and outlet ventilation systems. As a result, the environment was made safe and amenable for nearby residential properties.

1 quarter-energy-needs-will-generated-onsite-2025/

Wakefield Acoustics


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